Battery electrode composition comprising carbon and silicon with specific properties for superior performance

ABSTRACT

In an aspect, a lithium-ion battery anode composition comprises a porous composite particle comprising carbon (C) and an active material comprising silicon (Si), wherein the carbon is characterized by a domain size (r), as estimated from an atomic pair distribution function G(r) obtained from a synchrotron x-ray diffraction measurement of the porous composite particle, ranging from around 10 Å (1 nm) to around 60 Å (6 nm). In a further aspect, a carbon material for use in making an anode composition for use in a Li-ion battery is characterized by a domain size (r), as estimated from an atomic pair distribution function G(r) obtained from a synchrotron x-ray diffraction measurement of the carbon material, ranging from around 10 Å (1 nm) to around 60 Å (6 nm).

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application for patent is a Continuation of U.S.Non-Provisional application Ser. No. 17/930,366, entitled “BATTERYELECTRODE COMPOSITION COMPRISING CARBON AND SILICON WITH SPECIFICPROPERTIES FOR SUPERIOR PERFORMANCE,” filed Sep. 7, 2022, which in turnclaims the benefit of U.S. Provisional Application No. 63/241,407,entitled “BATTERY ELECTRODE COMPOSITION COMPRISING CARBON AND SILICONWITH SPECIFIC PROPERTIES FOR SUPERIOR PERFORMANCE,” filed Sep. 7, 2021,assigned to the assignee hereof, and expressly incorporated herein byreference in its entirety.

BACKGROUND Field

Aspects of the present disclosure relates generally to energy storagedevices, and more particularly to battery technology, supercapacitortechnology and the like.

Background

Owing in part to their relatively high energy densities, relatively highspecific energy, relatively high specific power, relatively fastcharging, light weight, and potential for long lifetimes and cycle life,advanced rechargeable batteries are desirable for a wide range ofelectronic devices, electric vehicles, grid storage and other importantapplications.

However, despite the increasing commercial prevalence of electrochemicalenergy storage technologies, further development of the batteries isneeded, particularly for potential applications in low- orzero-emission, hybrid-electrical or fully-electrical vehicles, consumerelectronics, energy-efficient cargo ships and locomotives, aerospaceapplications, and power grids. In particular, further improvements aredesired for various rechargeable batteries, such as rechargeable metaland metal-ion batteries (such as rechargeable Li and Li-ion batteries,rechargeable Na and Na-ion batteries, rechargeable Mg and Mg-ionbatteries, rechargeable K and K-ion batteries, rechargeable Ca andCa-ion batteries, etc.). The following energy storage devices maysimilarly benefit from the additional improvements: rechargeablehalogen-ion batteries (such as F-ion and Cl-ion batteries, etc.),rechargeable mixed ion batteries, rechargeable aqueous batteries (e.g.,rechargeable batteries with pH-neutral or acidic or causticelectrolytes), electrochemical capacitors (e.g., supercapacitors ordouble layer capacitors), hybrid devices, rechargeable polymerelectrolyte batteries and supercapacitors, rechargeable polymer gelelectrolyte batteries and supercapacitors, rechargeable solid ceramic orsolid glass electrolyte batteries, rechargeable composite electrolytebatteries, to name a few.

A broad range of active (charge-storing) materials, a broad range ofpolymer binders, a broad range of conductive additives and variousmixing recipes may be utilized in the construction of batteryelectrodes. In some designs, active materials may be utilized in theform of composite particles. However, for improved electrode performance(low and stable resistance, high cycling stability, high-ratecapability, acceptable energy, good volumetric capacity, etc.), theoptimal composite formulations need to be identified. Furthermore, thechoice of binders, additives, and mixing protocols needs to bediscovered for specific types, specific physical and chemicalproperties, and specific sizes of active particles. In many cases, thechoices of the composite particle architecture and compositions as wellas the composition of the electrodes are not trivial and can becounter-intuitive.

In many different types of rechargeable batteries, charge storingmaterials may be produced as (nano)composite powders, which may compriseconductive carbon. As a subset of such particles, conductive carbon maybe distributed not only on the surface, but also within the bulk of the(nano)composite particles. In principle, such a class of charge-storing(nano)composite particles may offer great promises for scalable (and, insome cases, sustainable) manufacturing and achieving good charge storageperformance characteristics. Unfortunately, it largely remains unclearwhat types and what properties of carbon would be advantageous in suchapplications of composite ((nano)composite) particles. In addition, itis further unclear how to achieve effective processing of such(nano)composite particles into electrodes that would result in goodperformance characteristics, including high capacity, fast charging,fast discharging, and long cycle stability. The performance of batteryelectrodes comprised of similar (nano)composites may become particularlypoor when the electrode capacity loading becomes moderate (forbatteries) (2-4 mAh/cm²) or even more so when it becomes high (e.g.,4-16 mAh/cm²). Higher capacity loading, however, is advantageous forincreasing battery cell energy density and reducing cell manufacturingcosts.

Accordingly, there remains a need for improved batteries, components,electrode materials and other related materials and manufacturingprocesses.

SUMMARY

The following presents a simplified summary relating to one or moreaspects disclosed herein. Thus, the following summary should not beconsidered an extensive overview relating to all contemplated aspects,nor should the following summary be considered to identify key orcritical elements relating to all contemplated aspects or to delineatethe scope associated with any particular aspect. Accordingly, thefollowing summary has the sole purpose to present certain conceptsrelating to one or more aspects relating to the mechanisms disclosedherein in a simplified form to precede the detailed descriptionpresented below.

In an aspect, a lithium-ion battery anode composition includes a porouscomposite particle comprising carbon (C) and an active materialcomprising silicon (Si), wherein the carbon is characterized by a domainsize (r), as estimated from an atomic pair distribution function G(r)obtained from a synchrotron x-ray diffraction measurement of the porouscomposite particle, ranging from around 10 Å (1 nm) to around 60 Å (6nm).

In some aspects, the carbon is characterized by one or more of thefollowing: (1) a domain size ranging between around 15 Å and around 19Å, (2) a domain size ranging between around 19 Å and around 22 Å, (3) adomain size ranging between around 24 Å and around 28 Å, and (4) adomain size ranging between around 28 Å and 55 Å, and the domain sizesare as estimated from the atomic pair distribution function G(r).

In some aspects, the carbon comprises porous carbon.

In some aspects, G(r=r₁) is a value of the atomic pair distributionfunction at a real space position of a first coordination sphere of thecarbon, wherein G(r=r₂) is a value of the atomic pair distributionfunction at a real space position of a second coordination sphere of thecarbon, and wherein a ratio G(r=r₁)/G(r=r₂) is in a range of around0.700 to around 0.590.

In some aspects, W(r=r₁) is a value of a full width at half maximum ofthe atomic pair distribution function at a real space position of afirst coordination sphere of the carbon, wherein W(r=r₂) is a value of afull width at half maximum of the atomic pair distribution function at areal space position of a second coordination sphere of the carbon; and aratio W(r=r₁)/W(r=r₂) is in a range of around 0.700 to around 0.850.

In some aspects, G(r=r₁) is a value of the atomic pair distributionfunction at a real space position of a first coordination sphere of thecarbon, wherein G(r=r₃) is a value of the atomic pair distributionfunction at a real space position of a third coordination sphere of thecarbon, and wherein a ratio G(r=r₁)/G(r=r₃) is in a range of around1.100 to around 1.300.

In some aspects, W(r=r₁) is a value of a full width at half maximum ofthe atomic pair distribution function at a real space position of afirst coordination sphere of the carbon, wherein W(r=r₃) is a value of afull width at half maximum of the atomic pair distribution function at areal space position of a third coordination sphere of the carbon, andwherein a ratio W(r=r₁)/W(r=r₃) is in a range of around 0.600 to around0.850.

In some aspects, an anode comprising the anode composition exhibits anareal capacity loading that ranges from around 2 mAh/cm² to around 16mAh/cm².

In some aspects, from around 10% to around 100% of the areal capacityloading of the anode is provided by composite particles that are eachconfigured as the porous composite particle.

In some aspects, the composite particles on average exhibit a silicon(Si) to carbon (C) weight ratio in the range from around 5:1 to 1:5.

In some aspects, the porous composite particle is characterized by anaverage scattering domain size (r), as estimated from the atomic pairdistribution function G(r), ranging from around 1 nm to around 40 nm.

In some aspects, the porous composite particle is characterized by theaverage scattering domain size (r) ranging from around 1 nm to around 10nm.

In some aspects, the porous composite particle on average comprises lessthan about 1 wt. % hydrogen (H), less than about 5 wt. % nitrogen (N)and less than about 2 wt. % oxygen (O).

In some aspects, the porous composite particle on average exhibitsuptake from around 1.5 wt. % to around 25 wt. % nitrogen (N) when heatedin a nitrogen gas (N₂) at 1050° C. for a period of 2 hours, as measuredon a powder that comprises the porous composite particle.

In some aspects, the porous composite particle exhibits average uptakefrom around 0.5 wt. % to around 10 wt. % nitrogen (N) when heated in anitrogen gas (N₂) at 850° C. for a period of 2 hours, as measured on apowder that comprises the porous composite particle.

In some aspects, the porous composite particle forms from around 1 wt. %to around 100 wt. % silicon carbide (SiC) when heated in a nitrogen gas(N₂) or in an argon gas (Ar) in a temperature range from around 750° C.to around 950° C. for a period of 2 hours or more, as detected by X-raydiffraction (XRD) or Fourier Transform Infrared Spectroscopy (FTIR).

In some aspects, the porous composite particle exhibits an averageBrunauer-Emmett-Teller (BET) specific surface area in the range fromaround 1 to around 40 m²/g, as measured using nitrogen sorption isothermon a powder that comprises the porous composite particle.

In some aspects, the porous composite particle exhibits average densityin the range from around 0.9 g/cm³ to around 2.2 g/cm³, as measuredusing nitrogen or argon pycnometry on a powder that comprises the porouscomposite particle.

In some aspects, the porous composite particle exhibits volume-averageparticle size in the range from around 0.2 micron to around 20 microns,as measured using scanning electron microscope (SEM) image analysis orparticle scattering techniques on a powder that comprises the porouscomposite particle.

In some aspects, Raman spectra of the porous composite particle exhibitscarbon D and G peaks, a ratio of average intensities of the D to G peaks(ID/IG) ranges from around 0.7 to around 2.7.

In an aspect, a Li-ion battery comprises an anode comprising thelithium-ion battery anode composition, a cathode that is electricallyseparated from the anode; and an electrolyte ionically coupling theanode and the cathode.

In some aspects, the battery capacity ranges from around 0.2 Ah toaround 400 Ah.

In some aspects, R(r=rSi—C) is a value of a radial distribution functionR(r) at a real space position of a first coordination sphere of a Si—Cpair in the porous composite particle, wherein R(r=rC—C) is a value ofthe radial distribution function R(r) at a real space position of afirst coordination sphere of a C—C pair in the porous compositeparticle, wherein the radial distribution function R(r) and the atomicpair distribution function are related by R(r)=G(r)r+4πr²ρ₀, ρ₀ being aconstant relating to a number density of scatterers, and wherein a ratioR(r=rSi—C)/R(r=rC—C) is in a range of 0.050 to around 1.000.

In an aspect, a carbon material for use in making an anode compositionfor use in a Li-ion battery, wherein the carbon material ischaracterized by a domain size (r), as estimated from an atomic pairdistribution function G(r) obtained from a synchrotron x-ray diffractionmeasurement of the carbon material, ranging from around 10 Å (1 nm) toaround 60 Å (6 nm).

In some aspects, the domain size (r) corresponds to one of thefollowing: (1) a first domain size ranging between around 15 Å andaround 19 Å, (2) a second domain size ranging between around 19 Å andaround 22 Å, (3) a third domain size ranging between around 24 Å andaround 28 Å, and (4) a fourth domain size ranging between around 40 Åand 55 Å.

In some aspects, the carbon material comprises porous carbon.

In some aspects, G(r=r₁) is a value of the atomic pair distributionfunction at a real space position of a first coordination sphere of thecarbon material, wherein G(r=r₂) is a value of the atomic pairdistribution function at a real space position of a second coordinationsphere of the carbon material, and wherein a ratio G(r=r₁)/G(r=r₂) is ina range of around 0.700 to around 0.590.

In some aspects, W(r=r₁) is a value of a full width at half maximum ofthe atomic pair distribution function at a real space position of afirst coordination sphere of the carbon material, wherein W(r=r₂) is avalue of a full width at half maximum of the atomic pair distributionfunction at a real space position of a second coordination sphere of thecarbon material, and wherein a ratio W(r=r₁)/W(r=r₂) is in a range ofaround 0.700 to around 0.850.

In some aspects, G(r=r₁) is a value of the atomic pair distributionfunction at a real space position of a first coordination sphere of thecarbon material, wherein G(r=r₃) is a value of the atomic pairdistribution function at a real space position of a third coordinationsphere of the carbon material, and wherein a ratio G(r=r₁)/G(r=r₃) is ina range of around 1.100 to around 1.300.

In some aspects, W(r=r₁) is a value of a full width at half maximum ofthe atomic pair distribution function at a real space position of afirst coordination sphere of the carbon material, wherein W(r=r₃) is avalue of a full width at half maximum of the atomic pair distributionfunction at a real space position of a third coordination sphere of thecarbon material, and wherein a ratio W(r=r₁)/W(r=r₃) is in a range ofaround 0.600 to around 0.850.

Other objects and advantages associated with the aspects disclosedherein will be apparent to those skilled in the art based on theaccompanying drawings and detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are presented to aid in the description ofembodiments of the disclosure and are provided solely for illustrationof the embodiments and not limitation thereof. Unless otherwise statedor implied by context, different hatchings, shadings, and/or fillpatterns in the drawings are meant only to draw contrast betweendifferent components, elements, features, etc., and are not meant toconvey the use of particular materials, colors, or other properties thatmay be defined outside of the present disclosure for the specificpattern employed.

FIG. 1 illustrates an example (e.g., Li-ion) battery in which thecomponents, materials, methods, and other techniques described herein,or combinations thereof, may be applied according to variousembodiments.

FIG. 2A is a graphical plot of Si crystallite size as a function ofsquare root of Raman D/G carbon peak intensity ratios for severalcarbon-based anode composite samples.

FIG. 2B is a graphical plot of Si crystallite size as a function oftemperature in one of the synthetic steps in the making of severalcarbon-based anode composite samples.

FIG. 3A is an x-ray diffraction pattern of two suitable porous carbonmaterials annealed at several vacuum annealing temperatures.

FIG. 3B is an x-ray diffraction pattern of another suitable porouscarbon material annealed at several vacuum annealing temperatures.

FIG. 3C illustrates another example of suitable porous carbons thatexhibit (002) carbon spacing exceeding that of graphite.

FIG. 4 is a graphical plot of nitrogen uptake (change in mass) as afunction of annealing temperature, for a carbon-containing compositepowder.

FIG. 5 is an x-ray diffraction pattern of suitable composite powder,containing C and Si, annealed in N₂ at different temperatures.

FIGS. 6A-6B show graphical plots of atomic pair distribution functionG(r) for several suitable carbon materials.

FIG. 7 shows graphical plots of atomic pair distribution function G(r)for several suitable carbon materials.

FIG. 8 shows graphical plots of atomic pair distribution function G(r)for: one suitable carbon material and two composite materials comprisingSi and C formed under differing synthesis and processing conditions.

FIG. 9A tabulates the ratios of the peak amplitudes (values of theatomic pair distribution function) of the first and second carbon-carboncoordination spheres, for illustrative carbon materials.

FIG. 9B shows the ratios of the values of full width at half-maximum(FWHM) of the atomic pair distribution function at the first and secondcarbon-carbon coordination spheres, for illustrative carbon materials.

FIG. 9C tabulates the ratios of the peak amplitudes (values of theatomic pair distribution function) of the first and third carbon-carboncoordination spheres, for illustrative carbon materials.

FIG. 9D shows the ratios of the values of FWHM of the atomic pairdistribution function at the first and third carbon-carbon coordinationspheres, for illustrative carbon materials.

FIG. 10 shows graphical plots of atomic pair distribution function G(r)for composite materials comprising carbon and silicon active material.

DETAILED DESCRIPTION

Aspects of the present invention are disclosed in the followingdescription and related drawings directed to specific embodiments of theinvention. The term “embodiments of the invention” does not require thatall embodiments of the invention include the discussed feature,advantage, process, or mode of operation, and alternative embodimentsmay be devised without departing from the scope of the invention.Additionally, well-known elements of the invention may not be describedin detail or may be omitted so as not to obscure other, more relevantdetails. Further, the terminology of “at least partially” is intendedfor interpretation as “partially, substantially or completely”.

Any numerical range described herein with respect to any embodiment ofthe present invention is intended not only to define the upper and lowerbounds of the associated numerical range, but also as an implicitdisclosure of each discrete value within that range in units orincrements that are consistent with the level of precision by which theupper and lower bounds are characterized. For example, a numericaldistance range from 7 nm to 20 nm (i.e., a level of precision in unitsor increments of ones) encompasses (in nm) a set of [7, 8, 9, 10, . . ., 19, 20], as if the intervening numbers 8 through 19 in units orincrements of ones were expressly disclosed. In another example, atemperature range from around −120° C. to around −60° C. encompasses (in° C.) a set of temperature ranges from around −120° C. to around −119°C., from around −119° C. to around −118° C., . . . from around −61° C.to around −60° C., as if the intervening numbers (in ° C.) between −120°C. and −60° C. in incremental ranges were expressly disclosed. In yetanother example, a numerical percentage range from 30.92% to 47.44%(i.e., a level of precision in units or increments of hundredths)encompasses (in %) a set of [30.92, 30.93, 30.94, . . . , 47.43, 47.44],as if the intervening numbers between 30.92 and 47.44 in units orincrements of hundredths were expressly disclosed. Hence, any of theintervening numbers encompassed by any disclosed numerical range areintended to be interpreted as if those intervening numbers had beendisclosed expressly, and any such intervening number may therebyconstitute its own upper and/or lower bound of a sub-range that fallsinside of the broader range. Each sub-range (e.g., each range thatincludes at least one intervening number from the broader range as anupper and/or lower bound) is thereby intended to be interpreted as beingimplicitly disclosed by virtue of the express disclosure of the broaderrange.

While the description below may describe certain examples in the contextof Li metal and Li-ion batteries (for brevity and convenience, andbecause of the current popularity of Li technology), it will beappreciated that various aspects may be applicable to other rechargeableand primary batteries (such as Na metal and Na-ion, Mg metal and Mg-ion,K metal and K-ion, Ca metal and Ca-ion and other metal and metal-ionbatteries, alkaline batteries with OH⁻ ions, mixed ion batteries, etc.)as well as electrochemical capacitors or hybrid devices (e.g., with oneelectrode being battery-like and another electrode being electrochemicalcapacitor-like).

While the description below may describe certain examples in the contextof active ions being contained within active particles, it will beappreciated that various aspects may be applicable to active ionsresiding in the electrolyte at some stage of the cell assembling orcharge or discharge.

Further, while the description below may also describe certain examplesof the active material formulations in a Li-containing (e.g., lithiated)state, it will be appreciated that various aspects may be applicable toLi-free (e.g., unlithiated) electrodes.

Further, while the description below may also describe certain examplesof the active electrode material belonging to so-called conversion-typeactive material(s) (including so-called alloying type active materials,true conversion-type active materials, chemical transformation-typeactive materials, metal active material, etc.), it will be appreciatedthat various aspects may be applicable to so-called intercalation-typeactive material(s), so-called pseudocapacitive active materials, as wellas mixed type active materials (or components of active materials) thatmay store charge by more than one mechanism (e.g., active materials thatexhibit both intercalation and conversion-type electrochemical reactionsduring cell operation, among many other combinations).

Further, while the description below may also describe certain examplesof active (reversibly ion-storing) materials (as component(s) of the(nano)composites) in the form of crystalline (or nanocrystalline)materials, it will be appreciated that various aspects may be applicableto highly disordered or amorphous active materials.

Further, while the description below may also describe certain examplesof active (reversibly ion-storing) materials as not based on carbon(e.g., comprising less than around 10 at. % of sp²-bonded carbon; insome designs—less than around 1 at. % of sp²-bonded carbon; in somedesigns—comprising from around 0 to around 1 at. % of carbon atoms), itwill be appreciated that carbon materials (including materials thatcomprise 90-100 at. % sp²-bonded carbon) may also reversibly store ionsin certain potential ranges of battery operation (although commonlyexhibiting a substantially smaller volumetric and gravimetric capacityfor ion storage). So, when discussing active materials in variousembodiments of this disclosure, the active material in thecarbon-containing composites may be characterized as “substantially moreactive than carbon” materials (e.g., storing at least 2 times more ionsper atom in the “active” material than in carbon in the operationalelectrochemical potential range).

Further, while the description below may also describe certain examplesof specific sources (precursors) of carbon materials, it will beappreciated that various aspects may be applicable to other types ofcarbon material sources, including those produced from both organic andinorganic precursors, those that utilize (e.g., sacrificial) templatesfor the formation of some of the pores, those that utilize organic wasteproducts, among others.

Further, while the description below may also describe certain examplesof (nano)composite particles or porous carbon particles having irregularor spherical or spheroidal three dimensional (3D) shape, it will beappreciated that various aspects may be applicable to particles havingother shapes, including, for example, elongated two-dimensional (2D,such as (nano)composite platelets or porous carbon sheets, etc.) or onedimensional (1D, such as, for example, (nano)composite nanofibers andfibers or porous carbon nanofibers and fibers, etc.) shapes.

Further, while the description below may also describe certain examplesof liquid organic electrolytes as components of electrochemical cells(batteries or electrochemical capacitors) based on the (nano)compositeelectrodes, it will be appreciated that various aspects may beapplicable to aqueous electrolytes, ionic salt electrolytes, molten saltelectrolytes, solid ceramic electrolytes, solid glass electrolyte, solidpolymer electrolytes (including single-ion conducting solid polymerelectrolytes, where one ion (e.g., cation) is mobile, while the counterion (e.g., anion) is chemically attached to the polymer backbone), gelelectrolytes, composite (e.g., glass-ceramic or glass-polymer orceramic-polymer or liquid-ceramic or liquid-polymer orliquid-ceramic-polymer or liquid-glass-polymer orliquid-glass-ceramic-polymer) electrolytes, and others. In some designs,more than one electrolyte could be used in a single cell construction(e.g., one electrolyte infiltrated/coating the surface of the electrodeor active material and another electrolyte interpenetrating remainingpores in the electrode(s) or comprising at least a part of the separatormembrane; or, as another illustrative example, one electrolytecontacting the anode and another electrolyte contacting the cathode).

In some examples and designs, the solid (at device operatingtemperatures) electrolytes may be melt-infiltrated into at least some ofthe pores within electrodes (e.g., at elevated temperatures, where theelectrolyte becomes liquid). In some examples and designs, the solid (atdevice operating temperatures) electrolytes may be dissolved into asolvent, infiltrated into at least some of the pores of the electrodes,followed by solvent evaporation (drying). In some examples and designs,the solid (at device operating temperatures) electrolytes may beinfiltrated into at least some of the pores of the electrodes in anintermediate stage when such electrolytes are liquid, followed by theconversion of the liquid into a solid. In some examples and designs, thepolymer electrolytes may be infiltrated into at least some of the poreswithin electrodes or active materials in a liquid state and polymerizedafter the infiltration (e.g., during heating or after sufficient storagein a suitable temperature range or UV treatment, etc.). In some designs,such polymerization may take place prior to cell use (application). Insome designs, such polymerization may take place after (e.g., or as afinal stage of) the cell assembling. In some designs, suchpolymerization may take place after (e.g., or as a final stage of) thecell sealing. In some designs, the remaining pores (if present) afterthe polymerization may be filled by another electrolyte in a fullyassembled device (such as a Li-ion battery cell).

During battery (such as a Li-ion battery) operation, intercalation-typeactive materials operate by insertion (intercalation) and extraction(de-intercalation) of Li ions into/from the interstitial positions(nanoscale or sub-nanoscale voids) present in crystalline or disorderedor fully amorphous structure of such intercalation compounds. Thisintercalation/de-intercalation process is accompanied by the changes inthe oxidation state of the non-Li atoms (ions) (e.g., such as transitionmetal ions). Chemical bonds typically do not break or reform during suchprocesses. Li ions diffuse in/out of the active materials.

During battery (such as a Li-ion battery) operation, conversionmaterials change (convert) from one crystal structure to another (hencethe name “conversion”-type). During (e.g., Li-ion) battery operation, Liions are inserted into alloying type materials forming lithium alloys(hence the name “alloying”-type). Sometimes, “alloying”-type electrodematerials (commonly metals and semimetals) are considered to be asub-class of “conversion”-type electrode materials. Known examples ofsuitable “alloying”-type active electrode materials for metal-ion (e.g.,Li-ion or Na-ion, etc.) batteries may include, but are not limited tosilicon (Si), tin (Sn), antimony (Sb), germanium (Ge), their variousalloys and combinations, among others.

“Alloying”-type electrode materials may also comprise other type(s) ofconversion materials (such as oxides, hydrides, nitrides, etc.) as minor(e.g., around 0.1%-50 wt. %) additions as well as less active materials(which may exhibit significantly lower, e.g., around 0.01%-30% of thealloying material gravimetric capacity) that may help to enhancemechanical or electrochemical stability of the alloying materials orenhance their electrical conductivity in a delithiated state (these maybe intercalation-type materials). The electrochemical reaction processesbetween Li ions and alloying or conversion materials may be accompaniedby the breakage of some of the original chemical bonds and the formationof new chemical bonds. In an ideal case for some designs, the process issomewhat reversible and only little (or no) loss of active material (orLi) takes place during the battery operation (e.g., preferably no morethan around 30% during the lifetime of a battery).

While the description below may describe certain examples in the contextof metal-ion batteries, other conversion-type electrodes that maybenefit from various aspects of the present disclosure include variouschemistries used in a broad range of aqueous batteries, such as alkalinebatteries, metal hydride batteries, lead acid batteries, etc. Theseinclude, but are not limited to, various metals (such as iron, zinc,cadmium, lead, indium, etc.), metal oxides, metal hydroxides, metaloxyhydroxides, and metal hydrides, to name a few.

FIG. 1 illustrates an example metal or metal-ion (e.g., Li or Li-ion)battery in which the components, materials, methods, and othertechniques described herein, or combinations thereof, may be appliedaccording to various embodiments. A cylindrical battery is shown herefor illustration purposes, but other types of arrangements, includingprismatic or pouch (laminate-type) batteries, may also be used asdesired. The example battery 100 includes a negative anode 102, apositive cathode 103, a separator 104 interposed between the anode 102and the cathode 103, an electrolyte (not shown) impregnating theseparator 104 (and typically impregnating both anode 102 and cathode103), a battery case 105, and a sealing member 106 sealing the batterycase 105. In some designs in case of solid electrolyte(s), a solidelectrolyte membrane may serve as a separator 104.

Both liquid and solid electrolytes may be used for the designs herein.Conventional electrolytes for Li- or Na-based batteries of this type aregenerally composed of a single Li or Na salt (such as LiPF₆ for Li-ionbatteries and NaPF₆ or NaClO₄ salts for Na-ion batteries) in a mixtureof organic solvents (such as a mixture of carbonates). Other commonorganic solvents that may be suitable in the context of one or moreembodiments of the present disclosure include nitriles, esters,sulfones, sulfoxides, phosphorous-based solvents, silicon-basedsolvents, ethers, and others. In some designs, some of such solvents mayalso be modified (e.g., be sulfonated or fluorinated). The electrolytesmay also comprise ionic liquids (in some designs, neutral ionic liquids;in other designs, acidic or basic ionic liquids). In some designs,suitable electrolytes may also comprise mixtures of various salts (e.g.,mixtures of several Li salts or mixtures of Li and non-Li salts forrechargeable Li and Li-ion batteries). The most common salt used incertain conventional Li-ion battery electrolyte, for example, is LiPF₆,while less common salts that may also be suitable in the context of oneor more embodiments of the present disclosure include lithiumtetrafluoroborate (LiBF₄), lithium perchlorate (LiClO₄), lithiumbis(oxalato)borate (LiB(C₂O₄)₂), lithium difluoro(oxalate)borate(LiBF₂(C₂O₄)), various lithium imides (such as SO₂FN (Li⁺)SO₂F,CF₃SO₂N⁻(Li⁺)SO₂CF₃, CF₃CF₂SO₂N⁻(Li⁺)SO₂CF₃, CF₃CF₂SO₂N⁻(Li⁺)SO₂CF₂CF₃,CF₃SO₂N⁻(Li⁺)SO₂CF₂OCF₃, CF₃OCF₂SO₂N⁻(Li⁺)SO₂CF₂OCF₃,C₆F₅SO₂N⁻(Li⁺)SO₂CF₃, C₆F₅SO₂N⁻(Li⁺)SO₂C₆F₅ or CF₃SO₂N⁻(Li⁺)SO₂PhCF₃,and others), and others. Electrolytes for Mg-ion, K-ion, Ca-ion, andAl-ion batteries may be more exotic as these batteries are in earlierstages of development. These exotic electrolytes may comprise differentsalts and solvents (in some cases, ionic liquids may replace organicsolvents for certain applications). In some designs, more than one Lisalt may advantageously be used in electrolytes. In some designs,electrolytes for Li-ion batteries may also advantageously comprisenon-Li salt(s).

In the case of aqueous Li-ion (or aqueous Na-ion, K-ion, Ca-ion, etc.)batteries, suitable electrolytes may include a solution (e.g., aqueoussolution or mixed aqueous-organic solution) of inorganic Li (or Na, K,Ca, etc.) salt(s) (such as Li₂SO₄, LiNO₃, LiCl, LiBr, Li₃PO₄, H₂LiO₄P,C₂F₃LiO₂, C₂F₃LiO₃S,Na₂O₃Se, Na₂SO₄, Na₂O₇Si₃, Na₃O₉P₃, C₂F₃NaO₂; etc.).In some designs, these electrolytes may also comprise solutions oforganic Li (or Na, K, Ca, etc.) salts, such as (listed with respect toLi for brevity) metal salts of carboxylic acids (such as HCOOLi,CH₃COOLi, CH₃CH₂COOLi, CH₃(CH₂)₂COOLi, CH₃(CH₂)₃COOLi, CH₃(CH₂)₄COOLi,CH₃(CH₂)₅COOLi, CH₃(CH₂)₆COOLi, CH₃(CH₂)₇COOLi, CH₃(CH₂)₈COOLi,CH₃(CH₂)₉COOLi, CH₃(CH₂)₁₀COOLi, CH₃(CH₂)₁₁COOLi, CH₃(CH₂)₁₂COOLi,CH₃(CH₂)₁₃COOLi, CH₃(CH₂)₁₄COOLi, CH₃(CH₂)₁₅COOLi, CH₃(CH₂)₁₆COOLi,CH₃(CH₂)₁₇COOLi, CH₃(CH₂)₁₈COOLi and others with the formulaCH₃(CH₂)xCOOLi, where x ranges up to 50); metal salts of sulfonic acids(e.g., RS(═O)₂—OH, where R is a metal salt of an organic radical, suchas a CH₃SO₃Li, CH₃CH₂SO₃Li, C₆H₅SO₃Li, CH₃C₆H₄SO₃Li, CF₃SO₃Li,[CH₂CH(C₆H₄)SO₃Li]_(n) and others) and various other organometallicreagents (such as various organolithium reagents), to name a few. Suchsolutions may also comprise mixtures of inorganic and organic salts,various other salt mixtures (for example, a mixture of a Li salt and asalt of non-Li metals and semimetals), and, in some cases, hydroxide(s)(such as LiOH, NaOH, KOH, Ca(OH)₂, etc.), and, in some cases, acids(including organic acids). In some designs, such aqueous electrolytesmay also comprise neutral or acidic or basic ionic liquids (fromapproximately 0.00001 wt. % to approximately 40 wt. % relative to thetotal weight of electrolyte). In some designs, such “aqueous” (or watercontaining) electrolytes may also comprise organic solvents (fromapproximately 0.00001 wt. % to approximately 40 wt. % relative to thetotal weight of electrolyte), in addition to water. Illustrativeexamples of suitable organic solvents may include carbonates (e.g.,propylene carbonate, ethylene carbonate, diethyl carbonate, dimethylcarbonate, ethyl methyl carbonate, fluoroethylene carbonate, vinylenecarbonate, and others), various nitriles (e.g., acetonitrile, etc.),various esters, various sulfones (e.g., propane sulfone, etc.), varioussultones, various sulfoxides, various phosphorous-based solvents,various silicon-based solvents, various ethers, and others.

Some electrolytes in some aqueous batteries (such as alkaline batteries,including nickel-metal hydride batteries, among others) may comprise analkaline solution (for example, a mixture of KOH and LiOH solutions).Some electrolytes in aqueous batteries (such as lead acid batteries) maycomprise an acidic aqueous solution (for example, H₂SO₄ aqueous solutionor HCl aqueous solution). Some electrolytes in aqueous batteries maycomprise an organic solvent as an additive. Some electrolytes in aqueousbatteries may comprise two or more organic solvent(s) or ionic liquid(s)or surfactant(s) as additive(s) or substantial components of theelectrolyte.

Conventional electrodes utilized in Li or Li-ion batteries may beproduced by (i) formation of a slurry comprising active materials,conductive additives, binder solutions and, in some cases, surfactant orother functional additives; (ii) casting the slurry onto a metal foil(e.g., Cu foil for most anodes used in Li or Li-ion batteries and Alfoil for most cathodes used in Li or Li-ion batteries as well as forhigh potential anodes used in Li-ion batteries, such as lithiumtitanate); (iii) drying the casted slurry to completely evaporate thesolvent; and (iv) optionally densifying the electrodes (e.g., bypressure calendaring). Instead of using such a solvent-based process forelectrode fabrication, in some designs it may be advantageous to use dryelectrode processing (without using solvents), including, but notlimited to, electrostatic coating.

Some aspects of the present disclosure deal with the formation ofcarbon-containing composite electrode materials. A broad range ofsuitable active materials may be utilized in such composite electrodematerials, the illustrative examples of which are described below.

Conventional cathode materials utilized in Li and Li-ion batteries maybe of an intercalation-type, whereby metal ions are intercalated intoand occupy the interstitial positions of such materials during thecharge or discharge of a battery. Such cathode materials typicallyexperience very small volume changes (e.g., around 0.1-8 vol. %) whenused in battery electrodes during charge and discharge. Such cathodematerials also typically exhibit high density (e.g., around 3.8-6 g/cm³)and are relatively easy to mix in slurries. Polyvinylidene fluoride, orpolyvinylidene difluoride (PVDF), is one of the most common binders usedin these electrodes. Carbon black is the most common conductive additiveused in these electrodes. However, such cathodes exhibit relativelysmall gravimetric and volumetric reversible capacities (e.g., less thanaround 200-220 mAh/g and less than 1 around 000 mAh/cm³, respectively).

Illustrative examples of suitable intercalation-type active cathodematerials that may be utilized in the context of this disclosure for Lior Li-ion cells include, but are not limited to: lithium nickel cobaltaluminum oxides (NCA—e.g., LiNi_(0.8)Co_(0.15)Al_(0.05)O₂, orLiNi_(x)Co_(y)Al_(z)O₂, where typically x+y+z≤1, which may additionallycomprise metals other than Co and Al for enhanced performance or reducedCo content), lithium nickel cobalt manganese aluminum oxides (NCMA),lithium nickel oxides (LNO—e.g., LiNiO₂ or others, which may alsocomprise metals other than Ni for enhanced stability), various lithiummanganese oxides (LMO—e.g., LiMnO₂ or LMO, or Li₂MnO₃, or LiMn₂O₄, amongothers), various lithium nickel manganese cobalt oxides (NCM—e.g.,LiNi_(0.33)Co_(0.33)Mn_(0.33)O₂, or LiNi_(0.8)Co_(0.1)Mn_(0.1)O₂ or,more generally, LiNi_(x)Co_(y)Mn_(z)O₂, where typically x+y+z≤1, or NCM,or NMC), various lithium nickel manganese oxide (LiNi_(0.5)Mn_(0.5)O₂,LiNi_(0.25)Mn_(0.75)O₂ or LiNi_(x)Mn_(y)O₂, where typically x+y≤1;LiNi_(0.5)Mn_(0.15)O₄ or LiNi_(x)Mn_(y)O₄, where typically x+y≤2 or,more broadly, NMO, which may also comprise metals other than Ni and Mnfor enhanced stability and may have a layered or spinel or othersuitable crystal structures), lithium cobalt oxide (LCO—e.g., in theform of LiCoO₂ or LiCo₂O₄, which may also comprise metals other than Cofor enhanced performance or reduced cost), lithium cobalt aluminumoxides (LCAO), lithium manganese phosphate (LMP), lithium titaniumsulfite (LiTiS₂), or lithium iron phosphate (LiFePO₄, LFP), lithiummanganese phosphate (LiMnPO₄), lithium manganese iron phosphate (LMFP),lithium cobalt phosphate (LiCoPO₄), lithium nickel phosphate (LiNiPO₄),lithium vanadium fluoro phosphate (LiVFPO₄), lithium iron fluoro sulfate(LiFeSO₄F), various Li excess materials (e.g., lithium excess (incl.rock salt) transition metal oxides and oxy-fluorides such asLi_(1.211)Mo_(0.467)Cr_(0.3)O₂, Li_(1.3)Mn_(0.4)Nb_(0.3)O₂,Li_(1.2)Mn_(0.4)Ti_(0.4)O₂, Li_(1.2)Ni_(0.333)Ti_(0.333)Mo_(0.133)O₂ andmany others), various high capacity Li-ion based materials with partialsubstitution of oxygen for fluorine or iodine (e.g., rock saltLi₂Mn_(2/3)Nb_(1/3)O₂F, Li₂Mn₂Ti_(1/2)O₂F,Li_(1.5)Na_(0.5)MnO_(2.85)I_(0.12), among many others) and many othertypes of Li-containing disordered, rocksalt (including cation-disorderedrocksalt), layered, tavorite, olivine, or spinel type active materialsor their mixtures comprising at least oxygen or fluorine or sulfur andat least one transition metal and other lithium transition metal (TM,e.g., Mn, Ni, Co, Nb, Ti, Ta, Fe, V, Mo, etc.) oxides or phosphates orsulfates (or mixed) cathode materials that rely on the intercalation oflithium (Li) and changes in the TM oxidation state. In some designs,such materials may be doped or heavily doped. In addition to Li-basedintercalation-type active materials, other examples ofintercalation-type active materials may be based on (e.g., similar)Na-ion intercalation compounds, K-ion intercalation compounds, Ca-ionintercalation compounds, among others. In addition to Li-containing (orNa-containing, K-containing, Ca-containing, etc.) intercalationcompounds, Li-free (or Na-free, K-free, Ca-free, etc.) version(s) ofsuch or similar materials may be utilized (e.g., titanium oxide oroxyfluoride, niobium oxide or oxyfluoride, cobalt oxide or oxyfluoride,nickel oxide or oxyfluoride, nickel-aluminum oxide or oxyfluoride,nickel-cobalt-manganese oxide or oxyfluoride, nickel-cobalt-aluminumoxide or oxyfluoride, iron oxide or oxyfluoride, iron phosphate, manyothers and their various mixtures, etc.).

Some of such active intercalation materials may experience a gradient incomposition or core-shell particle morphology. Some of such materialsmay be partially fluorinated or comprise some meaningful fraction offluorine (e.g., around 0.001-10 at. %) in their composition. In somedesigns, high-voltage lithium transition metal oxide (or phosphate orsulfate or mixed or other) cathodes where TMs and oxygen (O) arecovalently bonded, both TM and O may take part in electrochemicalreduction-oxidation (redox) reactions during charge and discharge(including, but not limited to, those oxides or phosphate or sulfate ormixed cathodes that may comprise at least around 0.25 at. % of Mn, Fe,Ni, Co, Nb, Mg, Cr, Mo, Zr, W, Ta, Ti, Hf, Y, Sc, La, Sb, Sn, Si, orGe). Note that Sc, Y and various lanthanides may often be considered“inner transition metals”.

In addition to or instead of intercalation-type active materials, somedesigns of the present disclosure may comprise so-calledpseudocapacitive (or mixed pseudocapacitive-intercalation-type) activematerials. Suitable examples of pseudocapacitive (or mixedpseudocapacitive-intercalation-type) active materials include, but arenot limited to, various (including mixed metal) oxides, hydroxides,oxyhydroxides, nitrides, oxynitrides, nitrates, phosphates,(oxy)phosphates, sulfides, sulfate hydroxide and other inorganic saltsof Ru, Fe, Mn, Cu, Ti, Bi, V, Ni, Nb, Ce, Zr, Ta, Co, Sn, Sb, Si, In,Zn, Mo, Pb, La, Y and their various mixtures and derivatives. Suchcompounds may also comprise Li, Na, Ca, Cs, Mg and K. In some designs,such compounds may comprise two, three, four or more metals. In somedesigns, such compounds may comprise at least one transition metal.

Conventional anode materials utilized in Li-ion batteries are also of anintercalation-type, whereby metal ions are intercalated into and occupyinterstitial positions of such materials during the charge or dischargeof a battery. Such anodes experience small or very small volume changeswhen used in electrodes (e.g., around 0.05-10 vol. %). However, suchanodes exhibit relatively small gravimetric and volumetric reversiblecapacities (typically less than around 200 mAh/g in case of lithiumtitanate (LTO) and typically less than around 370-400 mAh/g rechargeablespecific capacity in the case of lithium vanadate, graphite- or hardcarbon-based anodes and less than around 600 mAh/cm3 rechargeablevolumetric capacity at the electrode level without considering thevolume of the current collector foils).

Conversion-type active cathode materials may offer significantly higherspecific capacities than intercalation-type materials. Suitable examplesof these include, but are not limited to, metal fluorides, metalchlorides, metal sulfides, metal selenides, their various mixtures,composites and others. For example, fluoride-based cathodes may offeroutstanding technological potential due to their very high capacities,in some cases exceeding around 300 mAh/g (greater than around 1200mAh/cm³ at the electrode level). For example, in a Li-free state, FeF₃offers a theoretical specific capacity of 712 mAh/g; FeF₂ offers atheoretical specific capacity of 571 mAh/g; MnF₃ offers a theoreticalspecific capacity of 719 mAh/g; CuF₂ offers a theoretical specificcapacity of 528 mAh/g; NiF₂ offers a theoretical specific capacity of554 mAh/g; PbF₂ offers a theoretical specific capacity of 219 mAh/g;BiF₃ offers a theoretical specific capacity of 302 mAh/g; BiF₅ offers atheoretical specific capacity of 441 mAh/g; SnF₂ offers a theoreticalspecific capacity of 342 mAh/g; SnF₄ offers a theoretical specificcapacity of 551 mAh/g; SbF₃ offers a theoretical specific capacity of450 mAh/g; SbF₅ offers a theoretical specific capacity of 618 mAh/g;CdF₂ offers a theoretical specific capacity of 356 mAh/g; ZnF₂ offers atheoretical specific capacity of 519 mAh/g; AlF₃ also offers a hightheoretical capacity, although at low lithiation potential. AgF and AgF₂offer high theoretical specific capacities too and additionally exhibitvery high lithiation potential. Mixtures (for example, in the form ofalloys) of fluorides may typically offer a theoretical capacityapproximately calculated according to the rule of mixtures. The use ofmixed metal fluorides may sometimes be advantageous (e.g., may offerhigher rates, lower resistance, higher practical capacity, or longerstability). The use of metal fluorides mixed with metals may alsosometimes be advantageous (e.g., may offer higher rates, lowerresistance, higher practical capacity, or longer stability). In a fullylithiated state, metal fluorides convert to a composite comprising amixture of metal and LiF clusters (or nanoparticles). Examples of theoverall reversible reactions of the conversion-type metal fluoridecathodes may include 2Li+CuF₂↔2LiF+Cu for CuF₂-based cathodes or3Li+FeF₃↔3LiF+Fe for FeF₃-based cathodes. It will be appreciated thatmetal fluoride-based cathodes may be prepared in Li-free or partiallylithiated or fully lithiated states. In addition to fluorides, otherillustrative examples of conversion-type active electrode materials mayinclude, but are not limited to, various metal oxy-fluorides,sulfo-fluorides, chloro-fluorides, oxy-chloro-fluorides,oxy-sulfo-fluorides, fluoro-phosphates, sulfo-phosphates,sulfo-fluoro-phosphates, mixtures of metals (e.g., Fe, Cu, Ni, Co, Bi,Cr, other metals, their various mixtures and alloys, partially oxidizedmetals and metal alloys, etc.) and salts (metal fluorides (including LiFor NaF), metal chlorides (including LiCl or NaF), metal oxy-fluorides,metal oxides, metal sulfo-fluorides, metal fluoro-phosphates, metalsulfides, metal oxy-sulfo-fluorides, their various combinations, etc.),and other salts that comprise halogen or sulfur or oxygen or phosphorousor a combination of these elements, among others. In some designs, F inmetal fluorides may be fully or partially replaced with another halogen(e.g., Cl or Br or I, etc.) or their mixtures to form the correspondingmetal chlorides or metal fluoride-chlorides and other metal halidecompositions. In some designs, metal halides may be at least partiallydissolved in the electrolyte. In some designs, at least a portion ofactive material may be stored in a liquid form (e.g., in electrolyte).

Yet another example of a promising conversion-type cathode (or, in somecases, anode) material is sulfur (S) (in a Li-free state) or lithiumsulfide (Li₂S, in a fully lithiated state). In some designs, selenium(Se) may also be used together with S or on its own for the formation ofsuch cathode active materials.

In some designs, conversion-type active cathode materials may alsoadvantageously comprise metal oxides or mixed metal oxides. In somedesigns, such (nano)composites may advantageously comprise metalsulfides or mixed metal sulfides. In some examples, mixed metal oxidesor mixed metal sulfides may comprise lithium. In some examples, mixedmetal oxides may comprise titanium or vanadium or manganese or ironmetal. In some examples, lithium-comprising metal oxides or metalsulfides may exhibit a layered structure. In some examples, metal oxidesor mixed metal oxides or metal sulfides or mixed metal sulfides mayadvantageously be both ionically and electrically conductive (e.g., inthe range from around 10⁻⁷ to around 10⁺⁴ S/cm). In some examples,various other intercalation-type active materials may be utilizedinstead of or in addition to metal oxides or metal sulfides. In somedesigns, such an intercalation-type active material exhibits chargestorage (e.g., Li insertion/extraction capacity) in the potential rangeclose to that of S or Li₂S (e.g., within around 1.5-3.8 V vs. Li/Li⁺).

In some designs, the use of so-called Li-air cathodes (e.g., cathodeswith active material in the form of Li₂O₂, Li₂O, LiOH in theirlithiation state) or similar metal-air cathodes based on Na, K, Ca, Al,Fe, Mn, Zn and other metals (instead of Li) may similarly be beneficialdue to their very high capacities. In some designs, such cathode activematerials should ideally reversibly react with oxygen or oxygencontaining species in the electrochemical cell and may fully disappearupon full de-lithiation (metal removal). These are also considered tobelong to conversion-type cathodes.

Conversion-type anodes may offer specific capacities much higher thangraphitic carbon through reactions generalized by:nLi+M_(a)X_(b)↔aM+bLi_(n)X, where M may be a metal or semimetal(intermetallic), X is an anion (e.g., O in the case of anodes, but mayalso be N, S, P, F, etc.) or hydrogen (H). Suitable examples of suchconversion-type active anode materials include, but are not limited to,various oxides, nitrides, sulfides, phosphides, fluorides, hydrides,etc. In some designs, these may include fully or partially oxidizednon-carbon group IV elements (e.g., oxides or nitrides or sulfides orphosphides of Si, Ge, Sn or Pb) and fully or partially (e.g., oxides ornitrides or sulfides or phosphides) of Al, Ga, In, Sb, Bi, Fe, Ti, Mn,Cu, Ni, Co, V, and Zn, among others.

Alloying-type active materials sometimes are considered a sub-class ofconversion-type active anode materials. Alloying-type materials for usein Li-ion batteries also offer higher gravimetric and volumetriccapacities compared to intercalation-type anodes. Alloying-type activeanode materials also may offer lower irreversible first cycle lossescompared to the described above conversion-type anode materials (such asvarious oxides, nitrides, sulfides, phosphides or hydrides, etc.). Forexample, Earth-abundant silicon (Si) offers approximately 10 timeshigher gravimetric capacity and approximately 3 times higher volumetriccapacity compared to an intercalation-type graphite (or carbonaceoussoft carbon, hard carbon or graphite-like) anode. In some designs,“Si-based” active material may include Si or, alternatively, Si doped orheavily doped with nitrogen (N), phosphorous (P), boron (B) or otherelements or be alloyed with various other metals. As previouslydescribed, in addition to Si-based active material, other Si-comprisingactive material, such as silicon oxides (SiO_(x)) or oxynitrides(SiO_(x)N_(y)) or nitrides (SiN_(y)) or hydrides or other Sielement-comprising active material (including those that are partiallyreduced by Li or Mg), and Si-comprising metal alloys may be utilized(e.g., some Si-comprising active materials include Si atoms in theircompositions as in Si-based ceramics or metal alloys, but are notconsidered Si-based in this context, with Si-based active materialsgenerally encompassing doped, heavily doped or undoped Si). TheseSi-comprising active materials offer lower capacity relative to Si-basedactive material but offer reduced volume changes and typically improvecycle stability, although commonly at the expense of higher first cyclelosses or faster degradation or both. In addition to Si-based or(non-Si-based) Si-comprising active anode materials, other examples ofsuch high capacity (e.g., nanocomposite) anodes comprising alloying-type(or, more broadly, conversion-type) active materials include, but arenot limited to, those that are based on or comprise germanium (Ge),antimony (Sb), aluminum (Al), magnesium (Mg), zinc (Zn), gallium (Ga),arsenic (As), phosphorous (P), silver (Ag), cadmium (Cd), indium (In),tin (Sn), lead (Sb), bismuth (Bi), their various mixtures and alloys(with themselves or Si or other “inactive” metals, such as iron (Fe) orcopper (Cu), among others), and others. Similarly, such materials may bedoped or heavily doped and be in the form of oxides, oxynitrides,nitrides, hydrides or other metal or semi-metal comprising compounds.

Alloying-type active anode materials sometimes are considered asub-class of conversion-type active anode materials. Alloying-typeactive anode materials for use in Li-ion batteries also offer highergravimetric and volumetric capacities compared to intercalation-typeanodes. Alloying-type active anode materials also may offer lowerirreversible first cycle losses compared to the described aboveconversion-type anode materials (such as various oxides, nitrides,sulfides, phosphides or hydrides, etc.). For example, Earth-abundantsilicon (Si) offers approximately 10 times higher gravimetric capacityand approximately 3 times higher volumetric capacity compared to anintercalation-type graphite (or carbonaceous soft carbon, hard carbon orgraphite-like) anode. In some designs, as noted above, “Si-based” activematerial may include Si or Si doped or heavily doped with nitrogen (N),phosphorous (P), boron (B) or other elements or be alloyed with variousother metals. In addition to Si-based active material, otherSi-comprising active material, such as silicon oxides (SiO_(x)) oroxynitrides (SiO_(x)N_(y)) or nitrides (SiN_(y)) or hydrides orSi-comprising alloys or other Si element-comprising active material(including those that are partially reduced by Li or Mg) may beutilized. These Si-comprising active materials offer lower capacityrelative to Si-based active material but offer reduced volume changesand typically improve cycle stability, although commonly at the expenseof higher first cycle losses or faster degradation or both. In additionto Si-based or (non-Si-based) Si-comprising active anode materials,other examples of such high capacity (e.g., nanocomposite) anodescomprising alloying-type (or, more broadly, conversion-type) activematerials include, but are not limited to, those that are based on orcomprise germanium (Ge), antimony (Sb), aluminum (Al), magnesium (Mg),zinc (Zn), gallium (Ga), arsenic (As), phosphorous (P), silver (Ag),cadmium (Cd), indium (In), tin (Sn), lead (Sb), bismuth (Bi), theirvarious mixtures and alloys (with themselves or Si or other “inactive”metals, such as iron (Fe) or copper (Cu), among others), and others.Similarly, such materials may be doped or heavily doped and be in theform of oxides, oxynitrides, nitrides, hydrides or other metal orsemi-metal comprising compounds.

In some designs, pure Li metal may be used as active anode material insome aspects of the present disclosure (e.g., for use in combination ofporous carbon materials in the anode). In some designs, such anodes mayadvantageously comprise other material(s) in addition to carbon andlithium metal (e.g., alloying or conversion-type anode materials,polymers, etc.). In some designs, such composites may be in the form ofparticles that are cast and formed into an electrode using a binder bysuitable mechanism. In some designs, such Li metal-C composite anodesmay at least partially form during the first charge (after the cellconstruction) using metal ions (e.g., Li ions) from the Li-containingcathode active material. For example, Li metal may plate (beelectrodeposited) inside the pores of suitable carbon during the firstcharge. In some designs, it may be advantageous for at least a portionof such pores (e.g., around 10-100% of the pores) to remain free fromelectrolyte and available for Li metal deposition during cell operation.In some designs, pores within suitable porous carbon may be closed byforming a shell around the porous carbon (and/or by incorporatingpore-plugging material) before or after the electrode fabrication. Insome designs, solid electrolytes (e.g., polymer or inorganic orpolymer-inorganic composite) may be advantageously utilized in order toreduce side reactions, reduce first cycle capacity losses, reduceLi-dendrite formation and/or improve cell safety.

A broad range of alloying-type, metal, conversion-type active anode andcathode materials as well as intercalation-type and pseudocapacitor-typeactive anode and cathode materials may be successfully utilized in thecontext of the present disclosure. In some designs, such materials maybe utilized for the formation of carbon-containing composites. It may beadvantageous in some designs (e.g., when active material is loaded intocomposite particles or electrodes prior to electrode assembling intocells) to employ those active materials that have partial vapor pressurebelow around 10⁻¹⁰ torr at around 400 K (preferably below 10⁻¹³ torr ataround 400 K). For example, in some designs, electrodes may need to bedried at around 400 K prior to cell assembling and substantialevaporation of active material may not only induce contamination andcreate a safety hazard, but also severely reduce electrode uniformityand the resulting cell performance. In some designs, the electrodes maybe assembled from the electrode composition (e.g., comprising thecomposite particles) while in a discharged state.

In some designs in the context of the present disclosure, the followingpolymer binders may be successfully used in electrodes comprisingintercalation-type or conversion-type or mixed anode materials:polyvinylidene fluoride, or polyvinylidene difluoride (PVDF), varioussalts of carboxymethyl cellulose (CMC) such as Na-CMC and others,styrene-butadiene rubber (SBR), xanthan gum, polyvinyl chloride (PVC),polyacrylic acid (PAA) and its various derivatives including varioussalts of PAA (such as Na-PAA, Li-PAA, NH₄-PAA and others), alginic acidsand its various derivatives including various salts of alginic acid(e.g., Na-alginate, Li-alginate, Ca-alginate, Al-alginate, etc.),chitosan, butylacrylate, gum Arabic, guar gum, carrageenan, gelatin,polyvinyl alcohol (PVA) and their various mixtures and co-polymers.Carbon black is the most common conductive additive used in anodes,although single-wall, double-wall and multi-wall carbon nanotubes,exfoliated graphite (multi-layered graphene flakes) and metal nanowiresmay also be used in some designs.

In many applications and electrode designs, batteries withintercalation-type or conversion-type or mixed cathode materials or withintercalation-type or conversion-type (incl. alloying-type, such as Sior Sn, etc.) or mixed anode materials may exhibit sufficiently fastcharge and discharge rates (e.g., charging to around 80% of the maximumcapacity within around 10-60 minutes). In some applications (e.g., foreven faster rate performance (e.g., charging to around 80% of themaximum capacity within around 1-600 seconds with “regular” arealcapacity loading or for 1-6000 sec with “high” areal capacity loading)or for better cycle stability or for better calendar life or for betterperformance at low or at high temperatures or for reduced reactivitywith electrolyte or for higher capacity utilization or for otherperformance gains), it may be advantageous to produce compositescomprising such active materials for use in the electrodes of batteries(e.g., Li-ion or Na-ion batteries, among others).

In some designs, it may further be advantageous for such activematerial-comprising composites (e.g., in the form of compositeparticles) to comprise carbon due to carbon's high electricalconductivity, acceptable mobility for Li and other ions, good mechanicalproperties and good chemical and electrochemical resistance.

In some designs, it may be advantageous for such composites (e.g., inthe form of composite particles) comprising both active (ion storing)materials (including, but not limited to intercalation-type materials,conversion-type materials including alloying type materials,pseudocapacitive materials, mixed-type active materials, etc.) and(inactive) carbon to have a meaningful weight fraction of (non-carbon)active materials. In some designs, the fraction of such active materials(e.g., Si-based or Si-comprising active material(s) in case of C andSi-comprising anode composites, to provide an illustrative example) maypreferably range from around 20 wt. % to around 98 wt. % (in somedesigns, from around 20 wt. % to around 40 wt. %; in other designs, fromaround 40 wt. % to around 60 wt. %; in yet other designs, from around 60wt. % to around 80 wt. %; in yet other designs, from around 80 wt. % toaround 98 wt. %) in as-produced or as-used for electrode or batteryassembling stage. In some designs, the weight ratio of active materialto carbon may preferably range from around 1:4 to around 50:1 (in somedesigns, from around 1:1 to around 20:1). Too low fraction of activematerials may lead to undesirably low volumetric capacity, while toohigh fraction of active materials may lead to reduced rate andstability.

Note that in some designs, instead of or in addition to pureintercalation-type active materials or pure conversion-type activematerials, mixed materials that experience both intercalation andconversion-type electrochemical reactions may be utilized. In somedesigns, intercalation-type active material within the electrodes may bein the form of the individual particles bonded together (e.g., with abinder and optional conductive additives) to form an electrode or in theform of composite particles that comprise intercalation-type activematerial, where particles may be similarly bonded together to form anelectrode. Similarly, in some designs, conversion-type active materialwithin the electrodes may be in the form of the individual particlesbonded together (e.g., with a binder and optional conductive additives)to form an electrode or in the form of composite particles that compriseconversion-type active material, where particles may be similarly bondedtogether to form an electrode. In some designs, electrodes may bepurposely comprised of more than one material or material type (e.g.,comprise both intercalation-type active material and conversion-typeactive material). In some designs, the particles comprisingintercalation-type active material and the particles comprisingconversion-type active material may exhibit sufficiently different sizesand/or BET specific surface area. In addition to conversion-type andintercalation-type active materials, some of the materials may be ofpseudocapacitive-type or at least experience pseudocapacitive reactionsin addition to other energy storage electrochemical reaction mechanisms.

In some designs, the active material distribution within electrodes maycomprise 100% of such carbon-containing composites (e.g., in somedesigns, Si-comprising anode material composites in case of anodes forLi-ion batteries) or alternatively may comprise a mixture of compositesand “regular” active materials (e.g., graphite or soft carbon or hardcarbon or their various mixtures in case of anodes for Li-ionbatteries). In some designs, “regular” active materials may beintercalation-type active materials. In some designs, the suitable massfraction of the composite particles in such “mixed” electrodes may rangefrom around 1 to around 99 wt. % of all the active material particles(in some designs, from around 1 wt. % to around 5 wt. %; in otherdesigns, from around 5 wt. % to around 10 wt. %; in yet other designs,from around 10 wt. % to around 20 wt. %; in yet other designs, fromaround 20 wt. % to around 30 wt. %; in yet other designs, from around 30wt. % to around 40 wt. %; in yet other designs, from around 40 wt. % toaround 50 wt. %; in yet other designs, from around 50 wt. % to around 60wt. %; in yet other designs, from around 60 wt. % to around 70 wt. %; inyet other designs, from around 70 wt. % to around 80 wt. %; in yet otherdesigns, from around 80 wt. % to around 90 wt. %; in yet other designs,from around 90 wt. % to around 99 wt. %) in a given electrode (that isnot counting the weight of the binder, conductive and other additives aswell as the weight of the current collectors), depending on theproperties of such materials and also the requirements and demands of anapplication. In some designs, smaller than around 1 wt. % fraction maybe too small to make a substantial difference. Similarly, in somedesigns, larger than around 99 wt. % fraction, on the other hand, maylead to undesirable increase in the electrode mixing complexity and costand may be better replaced with around 100 wt. % of composite(s) withoutany substantial sacrifice with the electrode properties. However, anyfraction (from around 0 to around 100 wt. %) may be suitable for someapplications.

In some designs, the performance characteristics and cycle stability ofelectrodes comprising some of such carbon comprising composite materials(e.g., in the form of composite particles) may become particularlyunsatisfactory for applications requiring ultra-fast charging (e.g.,within around 1-600 seconds) or long calendar life or long cycle life orlow first cycle losses or other properties, particularly if theelectrode areal capacity loading exceeds around 1-2 mAh/cm², even moreif the electrode areal capacity exceeds around 4-5 mAh/cm², and furthermore if the electrode areal capacity exceeds around 6-8 mAh/cm² (e.g.,6-18 mAh/cm² or even more). Higher loading, however, is advantageous forreducing cost of energy storage devices and increasing their energydensity and specific energy. One or more embodiments of the presentdisclosure are directed to synthesis processes, compositions and variousphysical and chemical properties of carbon comprising compositeelectrodes that facilitate satisfactory performance for electrode arealoadings in the range from around 2 mAh/cm² to around 5 mAh/cm² and moreso for loadings in the range from around 5 mAh/cm² to around 8 mAh/cm²and even more so for loadings in the range from around 8 mAh/cm² toaround 16 or even around 18 mAh/cm² (e.g., in some designs, an aerialcapacity loading of an electrode composition may range from around 2mAh/cm² to around 18 mAh/cm²).

In some designs, degradation of Li-ion cells with some carbon-containingcomposite materials (e.g., in the form of the composite particlescomprising both carbon and active material(s)) in at least one of theirelectrodes (e.g., in an anode or in a cathode or in both) may becomeparticularly undesirably fast for multi-layered (e.g., stacked orrolled) medium sized cells (e.g., cells with cell capacity in the rangefrom 0.2 Ah to around 10 Ah), even more so for large cells (e.g., cellswith cell capacity in the range from around 10 Ah to around 40 Ah), evenmore so for ultra-large cells (e.g., cells with cell capacity in therange from around 40 Ah to around 400 Ah) or gigantic cells (e.g., cellswith cell capacity in the range from around 400 Ah to around 4,000 Ah oreven more). However, multi-layered medium or large size cells may beattractive for some electronic devices and multi-layered large,ultra-large or gigantic cells may be particularly attractive for use insome electric transportation or grid storage applications. One or moreaspects of the present disclosure facilitates utilization of particulartypes of carbon with suitable microstructural, chemical, physical andother properties in order to mitigate or overcome some or all of suchlimitations of carbon-containing composite materials and substantiallyenhance performance of such Li-ion cells

In some designs (e.g., for faster charging rate or for improvedstability, etc.) it may be advantageous for such carbon comprisingcomposites (e.g., carbon comprising composite particles) with(non-carbon) active materials to comprise pores (e.g., surface pores,closed internal pores that are inaccessible to external materials suchas electrolyte, open internal pores that are accessible to externalmaterials such as electrolyte, interconnected open internal pores,etc.). In some designs, it may be advantageous for the “total” porevolume (inclusive of closed internal pores, if any) in the composite torange from around 0.01 cm³/g to around 2.0 cm³/g (in some designs, fromaround 2 vol. % to around 75 vol. %), depending on the volume changes in(non-carbon) active materials during cycling, ionic conductivity of thecomposite components, degree of side reactions with electrolyte atoperating conditions and other factors. In some designs (e.g., whenvolume changes in active materials are small and when side reactions aremoderate, it may be advantageous for at least some portion (e.g., around0.1-100 vol. %) of all the pores in the composites to be accessible toelectrolyte while the electrode composition is made part of an energystorage device cell (e.g., in case of 100 vol. % in this context, thereare essentially no closed internal pores). In some designs, it may beadvantageous for at least some portion (e.g., around 1-100 vol. %) ofthe pores to be interconnected to neighboring pores and accessible fromthe interior (or center) of the composite particles. In some designs, itmay be advantageous for at least some portion (e.g., around 1-100 vol.%) of the pores to exhibit characteristic dimensions (e.g., diameter orwidth) in the range from around 0.3 nm to around 600 nm. In somedesigns, it may be advantageous (e.g., to maximize volumetric capacityof the electrodes, while attaining high-rate performance) for at leastsome fraction (e.g., around 0.1-30 vol. %) of all the pores (includingboth accessible and inaccessible to electrolyte when the electrodecomposition is made part of an energy storage device cell) to exhibitcharacteristic dimensions in the range from around 10 nm to around 100nm. In some designs, it may be advantageous (e.g., to maximizevolumetric capacity of the electrodes or to improve stability) for atleast some fraction (e.g., around 30-100 vol. %) of all the pores(including both accessible and inaccessible to electrolyte when theelectrode composition is made part of an energy storage device cell) toexhibit characteristic dimensions in the range from around 0.3 nm toaround 10 nm. In some designs, it may be advantageous (e.g., to maximizevolumetric capacity of the electrodes or to improve stability) for atleast some fraction (e.g., around 10-100 vol. %; in some designs around30-100 vol. %—such as around 30-40 vol. % or around 40-50 vol. % oraround 50-60 vol. % or around 60-70 vol. % or around 70-80 vol. % oraround 80-90 vol. % or around 90-100 vol. %) of all the pores (incomposites) to exhibit characteristic dimensions in the range fromaround 0.3 nm to around 6 nm. In some designs (e.g., when activematerials exhibit small (e.g., around 0.1-10 vol. %) or moderate (e.g.,around 10-120 vol. %) volume changes during cycling and maximizingvolumetric capacity of the electrodes and volumetric energy storagecharacteristics is desired), it may be advantageous for the volumefraction of all the pores in such composites to be small (e.g., around0.001-5 vol. %) or moderate (e.g., around 5-20 vol. %). In some designs(e.g., to maximize energy storage characteristics, such as power orenergy density or cycle stability or achieve a compromise between theseor other characteristics), it may be advantageous for the so-calledBrunauer-Emmett-Teller (BET) specific surface area (SSA) or densityfunctional theory (DFT) SSA of the composite electrode materials(particles) (e.g., as measured using N₂ or Ar or CO₂ or H₂ sorptiontechnique and analyzed using BET or DFT methods) to range from around0.25 m²/g to around 1000 m²/g (in some designs, from around 0.25 m²/g toaround 2 m²/g; in other designs, from around 2 m²/g to around 10 m²/g;in other designs, from around 10 m²/g to around 40 m²/g; in otherdesigns, from around 40 m²/g to around 100 m²/g; in other designs, fromaround 100 m²/g to around 400 m²/g; in other designs, from around 400m²/g to around 1000 m²/g, depending on the type of (non-carbon) activematerial and electrolyte used and depending on the desiredcharacteristics of the battery cells, among other factors). Larger SSAmay allow faster charge or discharge rate performance, but may also leadto higher fraction (rate) of some undesirable side reactions (e.g., withelectrolyte). The rate of such undesirable (e.g., leading toself-discharge or to gassing or to formation of deposits or to theirreversible consumption of electrolyte or to electrode or cellswelling, faster degradation, etc.) reactions may depend on theoperating electrode potential, operating temperature, and electrolytecomposition, among other factors. The acceptable rates depend on theparticular application. However, for many electrolyte systems and formost cell designs and applications, it may generally be preferable forthe BET SSA to range from around 0.25 m²/g to around 1000 m²/g. In somedesigns, it may be preferable for the BET SSA to range from around 1m²/g to around 100 m²/g. In some designs, it may be preferable for theBET SSA to range from around 1 m²/g to around 40 m²/g.

In some designs (particularly for higher BET SSE composites), it may beadvantageous for the active (e.g., intercalation-type or conversion-typeor mixed-type) materials to be protected (from undesirable interactionswith electrolyte) by a protective surface (shell) layer. In somedesigns, the suitable thickness of the protective surface layer mayrange from around 0.3 nm to around 60 nm (e.g., in some designs, fromaround 0.3 nm to around 3 nm; in some designs from around 3 nm to around6 nm; in some designs, from around 6 nm to around 10 nm; in somedesigns, from around 10 to around 20 nm; in some designs, from around 20nm to around 40 nm; yet, in some designs, from around 40 nm to around 60nm). Smaller thickness may be less effective for some applications,while larger thickness may lead to reduced rate performance of reducedvolumetric and gravimetric energy densities for some applications. Insome designs, the protective surface layer may directly coat at least aportion (e.g., around 1-100% of the outer surface area) of the activematerial(s)/particle(s) that otherwise would be exposed to electrolyteduring at least some time of the battery assembling or operation. Insome designs where the shell partially covers the outer surface area(e.g., protective material is applied selectively so as to predominatelycover particle surface regions that include pores that would otherwisebe open pores but are closed off by the protective surface layer, etc.),the protective surface layer may alternatively be characterized aspore-plugging material (rather than a shell). In some examples, theprotective surface layer may comprise carbon. In some examples, theprotective surface layer may comprise an oxide, a fluoride, anoxyfluoride, a sulfide, a nitride, an oxynitride, a nitride fluoride, aphosphate, a fluoro-phosphate (phosphate fluoride), or another materialthat comprises atoms of metals or semimetals. In some designs, theprotective surface layer material may comprise one or more of thefollowing elements: transition, alkali or alkaline-earth metal (such asiron (Fe), manganese (Mn), copper (Cu), yittrium (Y), zirconium (Zr),niobium (Nb), molybdenum (Mo), chromium (Cr), lithium (Li), sodium (Na),magnesium (Mg), potassium (K), calcium (Ca), strontium (Sr), cesium(Cs), barium (Ba), among others), lanthanum or lanthanoids (La, Ce, Gd,Nd, Eu, etc.), beryllium (Be), aluminum (Al), silicon (Si), gallium(Ga), germanium (Ge), phosphorous (P), arsenic (As), tin (Sn), bismuth(Bi), lead (Pb), indium (In), cadmium (Cd), zinc (Zn), fluorine (F),iodine (I), oxygen (O), nitrogen (N), sulfur (S), selenium (Se),tellurium (Te), hydrogen (H) and carbon (C).

In some designs (e.g., to maximize electrode uniformity and batterystability), it may be advantageous for such carbon comprising compositeelectrode particles to exhibit volume-average characteristics dimensions(e.g., diameter) in the range from around 5 nanometers (nm) to around150 microns (in some designs, from around 200 nm to around 30 microns),as measured using a scanning electron microscope (SEM) or a laserparticle size analyzer or a combination of several characterizationtechniques and numerical analyses/modeling. Too small of a particle sizemay lead to difficulties achieving high packing density for someapplications. At the same time, a high-volume fraction of smallerparticles may also result in small interparticle pore size, which mayslow down rate performance in the electrode and lead to faster celldegradation in some designs (particularly, if batteries are operating atfaster rates or at lower temperatures). Too large of an average particlesize, on the other hand, may lead to local variations in the electrodecapacity loading and may result in faster cell degradation in somedesigns (particularly if the battery is operating at lower temperaturesor at faster rates). The composite particle size, the interconnectivityof the pores in the composite as well as the ionic and electronictransport within the composite materials may affect the particle-levelrate performance. In some designs, too large of an average particle sizemay also result in poor (or insufficiently good for a given application)charge or discharge rate performance. While various electrode andelectrolyte properties, battery cell operational conditions (e.g.,current, rate, temperature, charge voltage, electrode operatingpotential, etc.), porosity and shape of the composite particles andother parameters may affect optimal composite particle size, it isadvantageous in some designs for such composite electrode particles toexhibit volume-average characteristic dimensions in the range fromaround 200 nm to around 30 microns (in some designs—from around 0.2micron to around 1 micron; in other designs from around 1 to around 2micron; in yet other designs from around 2 microns to around 5 microns;in yet other designs from around 5 microns to around 10 microns; in yetother designs from around 10 microns to around 30 microns). Suitableelectrode-level porosity (e.g., mostly—the volume fraction of the spacein the electrode filled by the electrolyte) may be affected by thevolume fraction of the binder, volume fraction of conductive and otheradditive and volume fraction of active (composite) particles (and theiropen porosity), electrolyte conductivity, electrode thickness, batteryoperation and other properties. Such porosity may also change duringcycling if active materials or composites comprising active materialexhibit substantial volume changes during cycling. However, values ofsuch electrode porosity ranging from around 1 vol. % to around 75 vol. %(e.g., in some designs—after 0-10 cycles after so-called battery“formation” and quality control stages; in some designs—after electrodeassembling/calendaring and prior to electrolyte infiltration in cells)are acceptable or advantageous for some applications (in somedesigns—from around 1 vol. % to around 10 vol. %; in other designs fromaround 10 vol. % to around 20 vol. %; in yet other designs from around20 vol. % to around 30 vol. %; in yet other designs from around 30 vol.% to around 40 vol. %; in yet other designs from around 40 vol. % toaround 50 vol. %; in yet other designs from around 50 vol. % to around60 vol. %; in yet other designs from around 60 vol. % to around 75 vol.%). Smaller volume fraction may lead to slow charging or dischargingrates and faster cell degradation in some applications. Larger fractionmay undesirably reduce volumetric energy density, rate performance andincrease battery costs in some applications. In some designs, the volumefraction of the electrode occupied (filled) with a suitable electrolytemay advantageously range from around 1 vol. % to around 75 vol. %. Insome designs, the suitable volume fraction of the electrode occupied(filled) with a suitable electrolyte may even be in narrower range, fromaround 5 vol. % to around 60 vol. % (or even in a narrower range, forexample, from around 10 vol. % to around 40 vol. %).

In some designs, a large portion (e.g., around 70-100 vol. %) of(non-carbon) active material within carbon comprising compositeelectrode particles may be in the form of smaller particles (ratherthan, e.g., in the form of continuous or discontinuous coatings or inthe form of a porous unibody that is filled with carbon or other(inactive or less active) materials). In some designs, thevolume-average size of active material particles (within the carboncomprising composite electrode particles) may advantageously range fromaround 0.5 nm to around 200 nm (in some designs, from around 0.5 nm toaround 5 nm; in other designs, from around 5 nm to around 10 nm; in yetother designs, from around 10 nm to around 20 nm; in yet other designs,from around 20 nm to around 40 nm; in yet other designs, from around 40nm to around 60 nm; in yet other designs, from around 60 nm to around100 nm; in yet other designs, from around 100 nm to around 200 nm). Toolarge size may not provide sufficiently fast electrochemical reactionsin some designs, while too small size may lead to undesirableside-reactions or too small mass loadings of active material particleswithin such composites, thus limiting energy characteristics of theenergy storage devices built with these composite particles in somedesigns. In some designs, the volume-average size of crystalline grainsof active material particles (within the prepared carbon comprisingcomposite electrode particles) may advantageously range from around 0.5nm to around 200 nm (in some designs, from around 0.5 nm to around 5 nm;in other designs, from around 5 nm to around 10 nm; in yet otherdesigns, from around 10 nm to around 20 nm; in yet other designs, fromaround 20 nm to around 40 nm; in yet other designs, from around 40 nm toaround 60 nm; in yet other designs, from around 60 nm to around 100 nm;in yet other designs, from around 100 nm to around 200 nm), as analyzedusing diffraction or scattering techniques (e.g., X-ray diffraction,XRD) or transmission electron microscopy (TEM) or other suitabletechniques.

In one illustrative example, porous composite anode powders for Li-ionbatteries with individual particles were prepared, comprising: (i)porous carbon infiltrated with (ii) silicon nanoparticles and enclosedin (iii) protective shelling material, wherein such a material comprisesclosed pores. XRD measurements of the porous composite anode powderswere conducted using a Rigaku SmartLab diffractometer utilizing a CuK-alpha radiation source, at scan rates between 0.5 and 10 degrees/minfrom 3 to 158 degrees 2-theta. Powder XRD data were collected in aBragg-Brentano geometry using X-ray wavelength of 1.5406 Å. Variousincident and detector optics were used, notably beam masks between 2-15mm, and Soller slits between 0.5 and 5°. A 2D silicon detector was usedfor all measurements. According to Scherrer analysis of the Si (111)Bragg peak, such porous composite anode powder samples demonstratedaverage Si crystallite size in the range from around 2 nm to around 100nm (in some composite particle designs, from around 2 nm to around 20nm; in other designs, from around 20 to around 40 nm; in yet otherdesigns, from around 40 to around 60 nm; in yet other designs, fromaround 60 to around 100 nm).

FIG. 2A illustrates some suitable composite particle designs with Siembedded within a porous carbon matrix material, where average Sicrystallite size determined using Scherrer analysis of the Si (111)Bragg peak was in the range from around 5 nm to around 16 nm. In FIG.2A, different color plots correspond to different experimental series ofsuitable Si- and C-containing composites produced.

FIG. 2B illustrates some other suitable composite particle designs withSi embedded within a porous carbon matrix material, where average Sicrystallite size determined using Scherrer analysis of the Si (111)Bragg peak was in the range from around 3.5 nm to around 8.5 nm.

Other suitable particle designs and yet other processing conditions mayresult in either larger (up to 60-100 nm, in some designs) or smaller(down to ˜2 nm) average Si grain sizes. In some suitable particledesigns and processing conditions, at least a portion of Si in thecomposite particles may be amorphous.

In some designs, it may be advantageous for the carbon in suchcarbon-containing composites (e.g., composite particles that are alsocomprising active (non-carbon) materials) to comprise mostly (e.g.,around 90-100%) sp²-bonded carbon atoms (e.g., in order to attain highelectrical conductivity or for other performance benefits). In somedesigns, it may be advantageous (e.g., for faster rate performance) forthe carbon to be sufficiently electrically conductive (e.g., withelectrical conductivity in the range from around 1 S/m to around 10⁶S/m).

In some designs, the active material particles (of the compositecarbon-containing electrode particles) may preferably be located inside(e.g., confined by) the pores of the suitable carbon particles. In somedesigns, from around 50 wt. % to around 100 wt. % of the active materialin the composite particles may be confined within pores defined in thecarbon particles.

In some designs, the composite carbon-containing and activematerial-containing electrode particles may comprise porous carbon. Insome process designs, porous carbon particles may be infiltrated withactive material (or active material particles) in at least one ofprocessing (or synthesis) stage to form such carbon-containing andactive material-containing electrode particles (e.g., Si-containingcomposite anode particles with Si-based active material and/orSi-comprising active material). In some designs, such a porous carbonmay exhibit specific properties that make composite particles performparticularly in Li-ion batteries and other related applications.

In some designs, it may be advantageous for the porous carbon (e.g., asused for the composite formation or eventually produced in the course ofthe composite formation) to exhibit an average so-called BET specificsurface area (SSA) (as measured by CO₂, N₂, H₂ or Ar gas sorption) inthe range from around 400 m²/g to around 5,000 m²/g (prior to formingcomposites). In some designs, it may be advantageous for the porouscarbon particles to exhibit open porosity in the range from around 35vol. % to around 93 vol. % and the total open pore volume (e.g., voidspace) in the range from around 0.3 cm³/g to around 6 cm³/g, asdetermined by gas sorption (e.g., CO₂, N₂, H₂, Ar, etc.) or othersuitable measurements. In some designs, the suitable BET SSA may rangefrom around 400 m²/g to around 1,000 m²/g; in other designs, thesuitable BET SSA may range from around 1000 m²/g to around 2,000 m²/g;in yet other designs, the suitable BET SSA may range from around 2,000m²/g to around 3,000 m²/g; in yet other designs, the suitable BET SSAmay range from around 3,000 m²/g to around 4,000 m²/g; in yet otherdesigns, the suitable BET SSA may range from around 4,000 m²/g to around5,000 m²/g, depending on the active material chemistry and properties ina battery, cell fabrication procedures, processing involved ininfiltrating active materials into the porous carbon, cell fabricationprocedures and other factors. BET SSA larger than 5,000 m²/g may make itdifficult to handle and produce composites, may also lead to inferiorperformance in some designs and, in some cases, be too expensive (forbattery applications) to produce and handle. BET SSA smaller than 400m²/g may undesirably limit rate performance and/or volumetric capacity(or capacitance) or other important properties of the composites in someelectrochemical energy storage applications. In some designs, thesuitable carbon pore volume may range from around 0.3 cm³/g to around 1cm³/g; in other designs, the suitable pore volume may range from around1 cm³/g to around 2 cm³/g; in yet other designs, the suitable porevolume may range from around 2 cm³/g to around 3 cm³/g; in yet otherdesigns, the suitable pore volume may range from around 3 cm³/g toaround 4 cm³/g; in yet other designs, the suitable pore volume may rangefrom around 4 cm³/g to around 5 cm³/g; in yet other designs, thesuitable pore volume may range from around 5 cm³/g to around 6 cm³/g,depending on the active material chemistry and properties in a battery,cell fabrication procedures, processing involved in infiltrating activematerials into the porous carbon, cell fabrication procedures and otherfactors. In some designs, the pore volume larger than around 6 cm³/g maymake it difficult to handle and produce composites, may also lead toinferior performance in some designs and, in some cases, be tooexpensive (for battery applications) to produce and handle. The porevolume smaller than 0.4 cm³/g may undesirably limit rate performanceand/or volumetric capacity (or capacitance) or other importantproperties of the composites in some electrochemical energy storageapplications.

In some designs, it may be advantageous for the porous carbon (for theuse in the formation of suitable electrode composites; for example, forinfiltration with active material or, for example, for making compositeswith active material precursors and subsequent conversion of the activematerial precursor to active material, etc.) to comprise near-spherical(or near-elliptical) pores. In some designs, it may be advantageous forsuch near-spherical (or near-elliptical) pores to exhibit average poresizes in the range from about 2 nm to about 100 nm (in some designs,from about 2 nm to about 20 nm; in other designs, from about 20 nm toabout 100 nm). In some designs, it may be advantageous for suchnear-spherical (or near-elliptical) pores to be separated from eachother by microporous (comprising mostly sub-2 nm pores) carbon material.Spherical (or near-spherical) pores exhibit better mechanical properties(e.g., compared to slit-shaped pores) and may better maintain mechanicalintegrity if filled with active material that exhibits volume changes(e.g., Si or Sn, etc.). Separating such (e.g., relatively large)spherical pores from each other and from the surface of the compositeparticles may help seal them to prevent undesirable interactions withelectrolyte. The mostly sub-2 nm pores in the material separating theindividual spherical pores may exhibit mostly slit-shape, in somedesigns. In some designs, the average thickness of the mostlymicroporous carbon “walls” separating the spherical pores may range fromabout 1 nm to about 100 nm (e.g., in some designs, from about 1 nm toabout 10 nm; in other designs, from about 10 nm to about 20 nm; in otherdesigns, from about 20 nm to about 50 nm; in yet other designs, fromabout 50 nm to about 100 nm). In some designs, the average pore volumeof such microporous carbon “walls” may range from about 0.05 cc/g toabout 1.20 cc/g (in some designs, from about 0.05 cc/g to about 0.25cc/g; in other designs, from about 0.25 cc/g to about 0.5 cc/g; in otherdesigns, from about 0.5 cc/g to about 0.75 cc/g; in yet other designs,from about 0.75 cc/g to about 1.20 cc/g), as determined, for example, bygas (e.g., N₂ or CO₂ or H₂ or Ar, etc.) sorption techniques. Too smallpore volume may undesirably reduce total carbon pore volume or abilityto infiltrate such particles with active material (e.g., Si) or reducerate performance or stability of the composite; while too large porevolume may undesirably reduce mechanical properties or reduce cyclestability of the (e.g., Si-comprising) composite.

In some designs, it may be advantageous for the porous carbon (for theuse in the formation of suitable electrode composites; for example, forinfiltration with active material or, for example, for making compositeswith active material precursors and subsequent conversion of the activematerial precursor to active material, etc.) to exhibit compositionalpurity of more than around 90 wt. % (e.g., less than 10 wt. % non-carbonspecies) prior to forming composites, as determined by chemicalcomposition, energy dispersive spectroscopy (EDS), thermo-gravimetricanalysis (TGA), combustion analyzer, X-ray photoelectron spectroscopy(XPS) or other suitable mechanism. In some designs, purity of more thanaround 96 wt. % is further advantageous in some designs. In somedesigns, prior to using in battery cells, the carbon purity of more thanaround 98-99 wt. % may be further advantageous. In some designs, theso-called “ash” content in carbon should preferably be less around 10wt. % (e.g., preferably less than around 4 wt. %, more preferably lessthan around 2 wt. %, even more preferably less than around 1 wt. %, andmost preferably below around 0.25 wt. %) prior to using such carbons inbattery electrodes (in some designs, prior to infiltrating with activematerials). In some designs, a higher content of various impurities(e.g., K, S, Ca, Na, Zn, P, O, etc.) may induce side reactions,significantly reduce cycle stability (particularly at elevatedtemperatures), induce premature failure, reduce gravimetric andvolumetric energy storage characteristics, reduce power density, lead toundesirably larger cell-to-cell or batch-to-batch variations andpossibly induce some sort of other undesirable outcomes that reduceperformance characteristics of electrochemical cells (e.g., Li-ionbatteries). In some designs, to attain high purity porous carbon, it maybe advantageous to use a combination of chemical (e.g., treatment inacids) and thermal (e.g., heat-treatment at temperatures from around800° C. to around 2000° C. and evaporation of impurities) purificationstages or use low content ash carbon precursors.

In some designs, it may be important for the porous carbon to compriseless than around 10 wt. % (e.g., preferably less than around 2 wt. %,more preferably less than around 1 wt. %; even more preferably less thanaround 0.5 wt. %) of hydrogen atoms (e.g., present within its structureor as part of the functional groups). In some designs, higher hydrogencontent (e.g., above around 2-10 wt. %) may lead to undesirableformation of gasses and cell swelling, reduced capacity utilization,reduced cycle stability, higher first cycle losses and/or otherundesirable reductions in performance characteristics. In some designs,it may be important for the composite carbon-containing electrodeparticles (e.g., Si-containing particles which include Si-based activematerial and/or Si-comprising active material in case of the anodematerial) to comprise less than around 10 wt. % (e.g., preferably lessthan around 2 wt. %, more preferably less than around 1 wt. %; even morepreferably less than around 0.5 wt. %) of hydrogen atoms. The hydrogencontent may be determined by using a hydrogen analyzer, titration,nuclear reaction analysis (NRA), Devanathan-Stachurski method,combustion carbon hydrogen nitrogen (CHN) analysis, Instrumental GasAnalysis (IGA), scanning Kelvin probe force microscopy (SKPFM) and othersuitable characterization mechanism.

Unexpectedly, thermal properties of carbon (e.g., porous carbon) usedfor (or used in) the formation of carbon-containing electrode compositeswere found to be an important indicator of its performance in Li-ionbatteries and related applications. In some designs, carbon (e.g.,porous carbon) used for (or used in) the formation of carbon-containingcomposites may preferably exhibit a specific range of crystallizationonset temperatures upon annealing in vacuum or inert environment, suchas Ar gas, for several hours (e.g., from around 1 h to around 6h), abovewhich XRD detects graphitization (formation of graphitic peak). In somedesigns, crystallization onset temperatures may preferably vary fromaround 1400° C. to around 2400° C. (in some designs, from around 1400°C. to around 1600° C.; in other designs, from around 1600° C. to around1800° C.; in yet other designs, from around 1800° C. to around 2000° C.;in yet other designs, from around 2000° C. to around 2200° C.; in yetother designs, from around 2200° C. to around 2400° C.). In somedesigns, the carbon XRD d(002) peak may shift as a function ofincreasing thermal anneal temperature from around 4.4-4.2 Å to around3.4 Å. Crystallization onset temperatures of porous carbon below around1400° C. or above around 2400° C. may undesirably result in the inferiorperformance of the carbon-containing composite particles in Li-ionbatteries and related applications.

In some designs, microstructure of carbon (e.g., porous carbon) used for(or used in) the formation of carbon-containing electrode composites wasfound to be an important indicator of its performance in Li-ionbatteries and related applications. In some designs, it was found thatthe (002) spacing of carbon should preferably range from around 4.40 Åto around 3.45 Å (in some designs, from about 4.40 Å to about 4.00 Å; inother designs, from about from about 4.00 Å to about 3.80 Å; in yetother designs, from about from about 3.80 Å to about 3.60 Å; in yetother designs, from about from about 3.60 Å to about 3.45 Å), dependingon various other parameters of the composites and their environment andelectrochemical operation potential in Li-ion battery cells.

FIG. 3A illustrate example of two suitable porous carbon samples thatexhibit crystallization onset temperature between 1600° C. and 1800° C.upon annealing in vacuum for around 1 hour, as indicated by theformation of sharp d(002) XRD peak upon annealing at 1800° C. FIG. 3Billustrate another example of a suitable porous carbon that exhibitcrystallization onset temperature between around 2100° C. and around2200° C. upon annealing in vacuum for around 1 hour, as indicated by theformation of sharp d(002) XRD peak upon annealing at 2200° C. FIG. 3Cillustrates another example of suitable porous carbons that exhibit(002) carbon spacing exceeding that of graphite, which is about 3.34 Å.

Certain physical and chemical properties of the carbon-containingcomposites were found to correlate well with their performance in cells.Such properties may be specific for the composition of active materialsand cell construction and operating parameters (e.g., electrolyte,amount of such composites in anodes and cathodes, areal capacityloadings, cell operating temperatures, charging rate, voltage ranges,among others). As such, as illustrative examples, certain properties ofcarbon-containing composites with Si-based active material (e.g.,near-pure Si) are disclosed that facilitate their superior performancein anodes (e.g., either as component of the anode together withgraphitic carbon material or as the only Li storing material in theanode, apart from very small Li storage in carbon-based conductiveadditives).

In some designs, it may be advantageous for such composites (e.g., inthe form of composite particles) comprising both active (ion storing)materials (including, for example, Si-based active materials, etc.) andcarbon to have a relatively small fraction of hydrogen. In some design,the fraction of hydrogen may preferably range from around 0.00 wt. % toaround 1.00 wt. % of the total weight of the composite particle (in somedesigns, below around 0.05 wt. %; in other designs, from around 0.05 wt.% to around 0.35 wt. %; in yet other designs, from around 0.35 wt. % toaround 1.00 wt. %). Too high a fraction of hydrogen may undesirably leadto excessive first cycle losses and faster degradation. Very lowfraction of H may be challenging to attain, provided other desiredstructural, chemical, physical and other properties of thecarbon-containing composites.

In some designs, it may be advantageous for such composites (e.g., inthe form of composite particles) comprising both active (ion storing)materials (including, for example, Si-based active materials, etc.) andcarbon to have a relatively small fraction of nitrogen. In some designs,the fraction of nitrogen (N) element may preferably range from around0.00 wt. % to around 5.00 wt. % of the total weight of the compositeparticle (in some designs, below around 0.5 wt. %; in other designs,from around 0.5 wt. % to around 1 wt. %; in yet other designs, fromaround 1 wt. % to around 2.50 wt. %; in yet other designs, from around2.5 wt. % to around 5.0 wt. %). Too high a fraction of N may undesirablylead to excessive first cycle losses and faster degradation. Very lowfraction of N may be challenging to attain, provided other desiredstructural, chemical, physical and other properties of thecarbon-containing composites.

In some designs, it may be advantageous for such composites (e.g., inthe form of composite particles) comprising both active (ion storing)materials (including, for example, Si-based active materials, etc.) andcarbon to have a relatively small fraction of oxygen. In some designs,the fraction of oxygen (O) may preferably range from around 0.00 wt. %to around 5.00 wt. % of the total weight of the composite particle (insome designs, below around 0.01 wt. %; in other designs, from around0.01 wt. % to around 0.25 wt. %; in yet other designs, from around 0.25wt. % to around 2 wt. %; in yet other designs, from around 2 wt. % toaround 5.0 wt. %). Too high a fraction of O may undesirably lead toexcessive first cycle losses and faster degradation. Very low fractionof O may be challenging to attain, provided other desired structural,chemical, physical and other properties of the carbon-containingcomposites.

It was unexpectedly found that values of the nitrogen (N) uptake duringannealing of (e.g., porous) carbon-based composites with Si (orSi-based) active material in a relatively inert nitrogen gas (N₂)correlate well with the performance of carbon-containing electrodecomposites in Li-ion batteries. For example, in some designs, it may bepreferable that during annealing of a suitable carbon-based andSi-comprising composites (e.g., composite particles with Si-based activematerial and/or Si-comprising active material) in nitrogen gas (N₂) fora period of 2 hours at 1050° C., the composite may exhibit nitrogenuptake (incorporation into carbon structure) in the range from around1.5 wt. % to around 25 wt. % nitrogen of the total weight of thecomposite (in some designs, from around 1.5 wt. % to around 2.5 wt. %;in other designs, from around 2.5 wt. % to around 7.5 wt. %; in yetother designs, from around 7.5 to around 15 wt. %; in yet other designs,from around 15 wt. % to around 25 wt. %), depending on the activematerial (e.g., Si-based active material and/or Si-comprising activematerial, etc.) particle size, fraction, cell designs and other factors.Either too little or too large nitrogen uptake may result in undesirablecell performance (e.g., lower cycle life; lower rate performance; lowerfirst cycle efficiency, etc.). In a further example, a suitablecarbon-based and Si-comprising composite on average exhibits uptake fromaround 1.5 wt. % to around 25 wt. % nitrogen (N) when heated in anitrogen gas (N₂) at 1050° C. for a period of 2 hours, as measured on apowder that comprises the composite particle. For example, the powdermay comprise mostly (e.g., all or substantially all or a majority, etc.)of carbon-based and Si-comprising composite particles (e.g., a largestatistical number of particles conducive for such a measurement).

In another example, in some designs, it may be preferable that duringannealing of a suitable carbon-based and Si-comprising composites (e.g.,composite particles with Si-based active material and/or Si-comprisingactive material) in nitrogen gas (N₂) for a period of 2 hours at 850°C., the composite particle may exhibit nitrogen uptake (incorporationinto carbon structure) in the range from around 0.5 wt. % to around 10wt. % nitrogen of the total weight of the composite (in some designs,from around 0.5 wt. % to around 2.5 wt. %; in other designs, from around2.5 wt. % to around 7.5 wt. %; in yet other designs, from around 7.5 toaround 10 wt. %), depending on the size of active material (e.g.,Si-based active material and/or Si-comprising active material, etc.)particle particles in the composites, active material wt. % in thecomposites, cell designs and other factors. Either too little or toolarge nitrogen uptake may result in undesirable cell performance (e.g.,lower cycle life; lower rate performance; lower first cycle efficiency,etc.). Conducting such annealing in N₂ tests may enable one to tuneprocessing and synthesis routes for the formation of such Si- andC-containing composites for superior performance in Li-ion batteryanodes.

FIG. 4 shows illustrative examples of the nitrogen (N) uptake byannealing of example suitable carbon-containing composite powder(comprising Si-based active material) in N₂ gas for 2 h. Higherannealing temperature results in larger N₂ gas uptake. The measurementerror is estimated to be less than around 1.5 wt. %.

Annealing of (e.g., porous) carbon-based composites with Si-based and/orSi-comprising active material in a relatively inert nitrogen gas (N₂) orargon gas (Ar) for, for example, 2 hours at high temperatures typicallyleads to the formation of silicon carbide (SiC) crystals, which could bedetected by X-ray diffraction (XRD) or by Fourier Transform InfraredSpectroscopy (FTIR) or other suitable technique. In someimplementations, the porous composite particle forms from around 1 wt. %to around 100 wt. % silicon carbide (SiC) when heated in a nitrogen gas(N₂) or in an argon gas (Ar) in a temperature range from around 750° C.to around 950° C. for a period of 2 hours or more, as detected by XRD orFTIR or other suitable techniques. The total weight of SiC may beidentified by using suitable calibration standards. In some designs, itmay be advantageous to oxidize Si or C remaining in the sample toincrease measurement precision. It was unexpectedly found that theminimum temperature at which SiC forms correlates with the performanceof carbon-containing electrode composites in Li-ion batteries. Forexample, in some designs, it may be preferable that during annealing ofa suitable carbon-based and Si-comprising composites in N₂ gas for 2 hthe minimum temperature needed for the SiC to be detected by XRD (e.g.,have SiC(111) XRD peak at 2-theta of around 35 degrees with intensity ofat least 10% of the Si(111) XRD peak at around 28 degrees, after thebackground subtraction) may preferably range from around 750° C. toaround 950° C. (in some designs, from around 750° C. to around 875° C.;in other designs, from around 875° C. to around 950° C.). Too high ortoo low SiC formation temperature typically results in inferiorperformance in Li-ion battery anodes.

FIG. 5 shows an illustrative example of the XRD patterns of the suitablecarbon-based Si-comprising composite annealed in N₂ at differenttemperatures and showing SiC formation at around 850° C.

It was unexpectedly found that the specific capacity (as measured inmAh/g) reduction (in %) upon annealing of suitable carbon-basedsilicon-containing anode composites (e.g., in the form of a powder) inN₂ gas at a relatively low temperature of 750° C. for 2 hours correlateswith their performance in Li-ion batteries (e.g., cycle stability,calendar life, rate performance, etc.). For example, in some designs, itmay be preferable that the capacity reduction during 2 h annealing in N₂ranges from around 2% to around 25% (in some designs, from around 2 toaround 12%; in other designs, from around 12 to around 25%). Too low ortoo high reduction in specific capacity upon annealing at suchconditions may result in reduced performance characteristics in Li-ionbattery anodes. As such, the synthesis and processing conditions for theformation of suitable carbon-containing and silicon-containing compositeanode particles may be tuned to attain the proper capacity reductions.

In some designs, it may be preferable for superior performance of porouscarbon-containing composites (e.g., comprising Si as part of an Si-basedor Si-comprising active material, among others), to exhibit a variableporosity across the diameter (cross-section) of the particles. In somedesigns (e.g., when active material exhibits substantial volume changesduring cycling, such as conversion-type active materials, such asSi-based and/or Si-comprising active material), it may be preferable forthe central part of the particles to comprise larger pore volume (e.g.,large volume fraction of pores relative to the fraction of activematerial or the fraction of active material and carbon combined) ascompared to the part of the particle closer to the surface.

In some designs, it may be preferable for superior performance of porouscarbon-containing composites (e.g., comprising Si as active material,among others), to comprise closed pores and a certain range of truedensities, as measured using an argon (Ar) pycnometry or, in somedesigns, nitrogen (N₂) pycnometry. In some designs when active materialin the carbon-comprising composite (particles) is Si-based orSi-comprising active material (e.g., Si or Si alloy or Si-based oxide ornitride or oxy-nitride or their various combinations (and preferablywhen the BET SSA is in the range from around 1 m²/g to around 40 m²/g)),it may be preferable for true (Ar pycnometry-measured or N₂pycnometry-measured) density of such composites to range from around 0.9g/cm³ to around 2.2 g/cm³, the optimum values being dependent on thefraction and type of Si-based or Si-comprising active materials, thepresence of other elements (e.g., metals), among other parameters. Insome designs, such a density may preferably range from around 0.9 g/cm³to around 1.4 g/cm³; in other designs, from around 1.4 g/cm³ to around1.8 g/cm³; in yet other designs, from around 1.8 g/cm³ to around 2.2g/cm³). Too low or two high densities may often lead to inferiorperformance (e.g., undesirably fast degradation, low rate performance,high losses, etc.).

In some designs, it may be preferable (for superior performance in Liion battery anodes) for the porous carbon-containing anode compositescomprising Si-based or Si-comprising active material (e.g., Si orSi-based active material (among other suitable active anode materials)),to exhibit a relatively uniform distribution of active material (e.g.,Si) and C, as measured by energy dispersive spectroscopy (EDS) on thecross-sections of such composite particles. In particular, apart fromthe 20-100 nm surface layer, in some designs, it may be preferable forthe EDS mapping (with, e.g., around 2-50 nm lateral resolution) on thecross-section of the composite particles to show less than around 50%deviation from the average Si:C ratio (of total elemental Si and totalelemental C in the composite particles) (which, for example, may be inthe range from 5:1 to 1:5, in some designs).

In some cell designs, it may be preferable for the for the porouscarbon-containing anode composites (e.g., composites comprising Si orSi-based or Si-comprising active material, among other suitable activeanode materials)) to be used in combination with intercalation-typeanode materials (e.g., synthetic/artificial or natural graphite, softcarbon, card carbon and their various combinations) in the formation ofanodes. In some designs, the suitable fraction of areal capacityprovided by the porous carbon-containing anode composites may range fromaround 10% to about 100%. For example, in some designs, for Li-ionbattery anodes with an areal capacity of, say, 3.5 mAh/cm², the porouscarbon-containing anode composites may provide from around 0.35 mAh/cm²to around 3.5 mAh/cm² of areal capacity. In some designs, the porouscarbon-containing anode composites may provide from around 10% to around25% of the areal capacity; in other designs, from around 25% to around50% of the areal capacity; in yet other designs, from around 50% toaround 75% of the areal capacity; in yet other designs, from around 75%to around 100% of the areal capacity, depending on the volume changes incarbon-containing anode composites during cycling, cell designs (e.g.,stacked vs. wound), cell operating conditions (e.g., temperature,charging rate, discharge rate, pulse current requirements, etc.), arealcapacity loadings, requirements for the cycle life and calendar life,requirements for the charging rate, restrictions on the electrolyte orelectrolyte additives selections, type of the copper foil used; totalareal loadings, among other requirements.

In some designs, it may be preferable (for superior performance in Liion battery anodes) for the porous carbon-containing anode compositescomprising Si or Si-based active material, to exhibit certainmicrostructural, structural, thermal (or more generally, physical) andchemical properties and certain microstructural, structural, thermal (ormore generally, physical) and chemical properties of its components(e.g., Si-based or Si-comprising active materials or carbon).

Unexpectedly, microstructural features of carbon (e.g., porous carbon)used for (or used in) the formation of carbon-containing electrodecomposites were found to be an important indicator of its performance inLi-ion batteries and related applications. As such, suitable processingof carbon should preferably be conducted in order to gain certainmicrostructural features for superior performance in some designs.Atomic pair distribution function analysis was found to be particularlyinsightful.

Atomic pair distribution function (APDF) or atomic PDF analysis is anXRD technique also commonly referred to as “total scattering analysis”.Herein, we sometimes refer to APDF as PDF. Most commonly, an XRDexperiment focuses on the crystallographic information held within theBragg diffraction of X-Rays from periodic structures within thecrystalline material in order to conduct phase identity, composition,purity, lattice parameters, atomic displacement, strain, crystallitesize, bond length, and angle, among others. However, many engineeredmaterials exhibit many aspects of their structure that deviate from thatof a perfect crystal; for example, exhibit very little or even nolong-range structural coherence.

A total scattering approach to X-ray structural characterizationconsiders both the Bragg (coherent scattering for crystalline materials)and diffuse scattering (incoherent scattering). When analyzing the totalsum of scattering in a diffraction experiment additional corrections aretypically used to account for background resulting from Comptonscattering, air scatter, and fluorescence, to name a few. Thisnormalized function is termed I(Q), and can be defined further as:

I(Q)=I _(Bragg) +I _(Diffuse) +I _(coherent) +I _(incoherent) +I_(background)   (Equation 1)

To subtract Compton scattering from this function knowledge of thechemical composition of the sample is necessary. The intensity of X-rayscattering as a function of the scattering vector I(Q) is typicallyfurther normalized correcting for the X-ray absorbance of the sampleresulting in the function S(Q), where S(Q) is defined as:

$\begin{matrix}{{S(Q)} = \frac{I(Q)}{\left\langle b \right\rangle^{2}}} & \left( {{Equation}2} \right)\end{matrix}$

where S(Q) is the diffraction from the sample normalized by the incidentflux per atom in the sample and is termed the total scattering structurefunction. In Equation 2, <b> is the average scattering factor of atomswithin the sample. Q is the scattering vector, which is the differencebetween the scattered wave vector and the incident wave vector. Themagnitude of the scattering vector Q is given by 4π sin θ/λ, where 2θ isthe angle between the incident and scattered x-rays and λ is the x-raywavelength.

that the X-Ray diffraction is a reciprocal space measurement resultingin data with units of Å¹, while the atomic pair distribution function isa real space function with units of Å.

$\begin{matrix}{{G(r)} = {\frac{2}{\pi}{\int_{Qmin}^{Qmax}{{Q\left\lbrack {{S(Q)} - 1} \right\rbrack}{\sin\left( {Qr} \right)}dQ}}}} & \left( {{Equation}3} \right)\end{matrix}$

The pair distribution function G(r) is the Fourier transformation of thetotal scattering structure function S(Q). The peaks of the pairdistribution function G(r) whose positions are independent of theFourier transform parameters represent atom-atom pairs in real space,with real space distances in units of Å between them. The existence ofthese peaks indicates that there are statistically significantpopulations of atoms exhibiting these real space atom-atom separationdistances. Data from a total scattering experiment requires minimalstructural coherence within the material and is therefore an excellenttechnique for the analysis of amorphous, nanocrystalline, or low ordermaterials, including carbons (e.g., porous carbons). Detailed structuralinformation may be gained from the APDF even when a model-based approachis not utilized. Some structural characteristics that may be probed bydirect analysis of the G(r) are: scattering domain size, coordinationnumber, atomic density, and a broad variety of information from peakanalysis and quantitative comparison across various atom-atom pairs.Scattering domain size may be determined by observing the radialdistance at which structural coherence is no longer present.Coordination number is available through integration of the peak in theG(r) as the intensity of that peak is a direct measure of the quantityof atom-atom pairs. In the context of carbonaceous materials, this maylead to, for example, a determination of sp²:sp³ carbon ratio, as thecoordination numbers for these are 3 and 4, respectively. Atomicdensity, a value that truly differs from macroscopic measurementtechniques in that it is not affected by trapped porosity in a material,may be found through careful analysis of the G(r). Determination ofatomic density relies on the fact that at G(r)=0 at radial distancesbelow that of the first atom-atom interactions in the material. At theselow radial distances, the slope of G(r)=−4πρ₀r² allows the atomic numberdensity to be directly determined by a linear fit of the G(r). Finally,a rich set of information may be gained by analysis of the peaks withinthe G(r). Examples of notable peak metrics for structural analysisinclude: peak position, full width at half maximum, peak height, andratios of width and height across various atom-atom pairs.

Also note that for analysis of data, it is common to convert the pairdistribution function G(r) to a radial distribution function, R(r). Therelationship between the pair distribution function, G(r), and theradial distribution function, R(r), is as follows (ρ₀ is a numberdensity of scatterers in the object):

R(r)=G(r)r+4πr ²ρ₀  (Equation 4)

Following the mathematical transformation to R(r), it is straightforwardto fit peaks of interest using a Gaussian function, from which area,width, height, and position are available.

In some illustrative examples, Synchrotron XRD data was collected on (i)suitable composite anode powders comprising both carbon (porous carbon)and Si active material and (ii) suitable porous carbon material utilizedfor the formation of suitable composite electrode powders. Such XRDexperiments were conducted at beamline 11-ID at the Advanced PhotonSource at Argonne National Laboratory. An X-Ray wavelength of 0.21150 Åwas used. Collected data were 2D plate images which were fit andintegrated using GSASII software for further analysis. Data werecollected at detector distances of 1000 and 180 mm with collection timesof 1 to 5 minutes.

Fourier Transforms were conducted using xPDFsuite with the followingtransform conditions. Diffraction data were plotted in Q, where Q is thevector that describes the moment of scattering to discuss diffractiondata independent of X-Ray wavelength/energy (Q=4π·sin(Theta)/λ), where λis the X-ray wavelength. The Q_(max) (Instrument) is the maximum Qcutoff (for a particular instrument) for the meaningful inputintensities in inverse ångströms (note that some data files may containtrailing zeros or unreliable intensities at the upper bound of thedetector range and so the Q_(max) (Instrument) defines a threshold forthe reliable data). This parameter is also used as an upper boundary forthe polynomial fit correction of the S(Q) data. Q_(max) (Instrument) isdefined independently of the Q_(max) used in the Fourier transform. TheQ_(min) is the lower Q-limit for the Fourier transformation of the F(Q)curve in inverse ångströms. The Q_(max) is the upper Q-limit for theFourier transformation of the F(Q) curve in inverse ångströms. Ther_(poly) is the r-limit for the maximum frequency in the F(Q) correctionpolynomial. The pair distribution function (PDF) may be unreliable atshorter r, however a very small r_(poly) would disable polynomialcorrection and give noisy PDF. Larger values would produce closer fitswith a higher degree polynomial, but when too large, they mightsmooth-out a useful signal in the data. The default was set to 0.9. Ther_(step) is the spacing of the r-grid for the calculated PDF inångströms (number of points in G(r)).

Fourier Transforms where conducted on the collected data using xPDFsoftware suite with the following conditions and assumptions: (i) priorto transformation the collected data was corrected by subtracting datafrom an empty polyimide (KAPTON) capillary sample holder to eliminatecontribution from the sample holder and air scattering effects; (ii)suitable high-purity porous carbon materials were considered to compriseonly carbon (the following values for used for analysis:Q_(max)(instrument)=29.0; Q_(min)=0.99984; Q_(max)=23.4697; Q_(max) wasselected such that spurious artifacts in F(Q) are truncated and suchthat F(Q) terminates at 0; r_(step)=0.01; r_(poly)=0.8898); (iii)suitable composite anode powders comprising both high purity carbon andhigh purity Si active material were considered to comprise only carbonand silicon in atomic ratio carefully determined by a combination ofother techniques, such as inductively-coupled plasma-mass spectrometry(ICP-MS), inductively-coupled plasma-optical emission spectrometry(ICP-OES), gravimetric burnout data, recording mass gains duringsynthesis and other methods (the following values for used for analysis:Q_(max)(instrument)=28.998; Q_(min)=0.71731; Q_(max)=23.0; Q_(max) wasselected such that spurious artifacts in F(Q) are truncated and suchthat F(Q) terminates at 0; r_(step)=0.01; r_(poly)=0.9); (iv)determination of ρ₀ for the conversion of G(r) to R(r) in Equation 4 wasachieved through a Nonlinear Least Squares (nls) fit of the slope of theG(r) between r=0 and r=0.75 Å; some adjustments were made to account forany concentrated error built up at low radial distances such that R(r)does not fall below R(r)=0. The domain size (the size of coherentlyscattering structural domains, averaged over the material within thebeam path) was calculated from the PDF data. The domain size (r) wasestimated by the dimensions (r) above which one observes the loss ofsubstantial coherence, as defined by the function G(r) falling belowaround +/−0.01. Note that for crystalline nanoparticles the coherencelength is equal to the nanoparticle size, but for nanoparticles withdefects or with diameter-dependent structural relaxation the coherencelength is not equal to the nanoparticle size. So, the scatteringcoherence length places a robust lower bound on the average nanoparticlesize (“at least this size”), which may be larger. This is particularlyuseful for materials that do not display Bragg scattering (e.g.,amorphous or highly disordered), which cannot be typically analyzedusing Scherrer analysis.

The average domain size of suitable carbon (e.g., porous carbon) usedfor the formation of (or used in) carbon-containing electrode composites(e.g., composite particles) may preferably (for good performance incells) range from around 10 Å to around 60 Å, with the most preferabledomain size depending on the composite composition and microstructure(e.g., type and amount of active material (e.g., Si vs. LTO vs. LiF/Fevs. NaCl vs. FeF₃, etc.), size of active material particles, volumeexpansion of active material, pore volume remaining in the composite,pore size, etc.) and a particular cell design and cell operatingconditions (e.g., electrochemical potential during cycling, types ofactive ions (e.g., Li⁺ vs. Na⁺), operating temperature, etc.). In somedesigns, such a suitable domain size in carbon may preferably range fromaround 10 Å to around 15 Å; in other designs, from around 15 Å to around25 Å; in yet other designs, from around 25 Å to around 30 Å; in yetother designs, from around 30 Å to around 40 Å; in yet other designs,from around 40 Å to around 50 Å; in yet other designs, from around 50 Åto around 60 Å. Such Synchrotron XRD measurements and PDF analysis maybe conducted either on the carbon materials (e.g., to select propersynthesis/processing conditions) or on the carbon-containing composites(e.g., with Si-based or Si-containing active material) (e.g., to detectthe presence or retention of suitable carbon in the composites).

FIGS. 6A-6B show illustrative examples of PDF analysis of suitablecarbons with a scattering domain size of (601) between around 15 Å andaround 19 Å (where loss of coherence is defined as the function fallingbelow G(r)=+/−0.01); (602) around 19 Å and around 22 Å; (603) betweenaround 24 Å and around 28 Å; (604) between 40 Å and 55 Å. SuchSynchrotron XRD measurements and PDF analysis may be conducted either onthe carbon materials (e.g., to select proper synthesis/processingconditions) or on the carbon-containing composites (e.g., with Si basedor Si containing active material, among others) (e.g., to detect thepresence or retention of suitable carbon in the composites).

FIG. 7 shows illustrative examples of PDF analysis of suitable carbonswith a scattering domain size of ˜17.5 Å, ˜21 Å, ˜26 Å and ˜45 Å.

In some designs, the average scattering domain size of suitablecarbon-containing and suitable active material-containing electrodecomposites (e.g., composite particles) may preferably (for goodperformance in cells) range from around 1 nm to around 40 nm, with themost preferable domain size depending on the composite composition andmicrostructure (e.g., type and amount of active material (e.g., Si basedvs. Si containing vs. LTO vs. LiF/Fe vs. NaCl vs. FeF₃, etc.), size ofactive material particles, volume expansion of active material, porevolume remaining in the composite, pore size, etc.) and a particularcell design and cell operating conditions (e.g., electrochemicalpotential during cycling, types of active ions (e.g., Li+ vs. Na+),operating temperature, etc.). In some designs, such a suitable domainsize may range from around 1 nm (10 Å) to around 5 nm (50 Å); in otherdesigns, from around 5 nm to around 10 nm; in yet other designs, fromaround 10 nm to around 20 nm; in yet other designs, from around 20 nm toaround 40 nm.

The average scattering domain size of active material (e.g., Si-basedand/or Si-comprising active material in case of anodes for Li-ionbatteries) in suitable carbon-containing electrode composites (e.g.,composite cathode or anode particles) may preferably (for goodperformance in cells) range from around 1 nm to around 40 nm, with themost preferable domain size depending on the composite composition andmicrostructure, a particular cell design and cell operating conditions.In some designs, such a suitable domain size may range from around 1 nm(10 Å) to around 5 nm (50 Å); in other designs, from around 5 nm toaround 10 nm; in yet other designs, from around 10 nm to around 20 nm;in yet other designs, from around 20 nm to around 40 nm.

FIG. 8 shows illustrative examples of PDF analysis of (i) suitablecarbon (suitable porous carbon in this example) used in the formation ofcarbon-containing electrode composites and (ii) two carbon-containinganode composites comprising Si-based active material. In oneillustrative example, the composite domain size is around ˜2.5 nm(limited by the Si domain size). In another illustrative example, thedomain size is around ˜3.5 nm (limited by the Si domain size; theincreased Si scattering domain size relative to the first example wasdue to deviation in the synthesis/processing conditions). Other suitableprocessing conditions may further increase Si scattering domain size(e.g., up to 5 nm in some cases or up to 10 nm in other cases or up to20 nm in yet other cases or even up to 40 nm yet other cases).

In the case of a perfect crystalline graphite, the real space centermaximum values for the first 3 coordination spheres of carbon are 1.42,2.45, and 2.85 Å. The first coordination sphere is defined as a spheredefined by atoms with the shortest real space distance to a centralreference atom. Atoms sitting in real space positions at fartherdistances from a central reference atom will fall into 2nd, 3rd, up tonth coordination spheres defined by their distance from the centralatom. These bond lengths or peak center maximums, however, can beshifted substantially if the structure of carbon is substantiallydistorted (e.g., as in some porous or structured or partially disorderedcarbons) or if the ratio of sp²:sp³ carbon changes significantly. For aperfect crystalline graphite, the ratio of the heights of the real spacepeaks for the first and second coordination sphere should be equal to0.5. However, disordered carbon (e.g., with vacancies or non-hexagonalrings) may exhibit higher ratios. In some designs of suitable carbon(e.g., porous carbon) used for (or used in) the formation ofcarbon-containing electrode composites (e.g., in the form of compositeparticles), synchrotron PDF peaks' height and their full width at halfmaximum (FWHM) within the first 3 coordination spheres may preferably(for good performance in cells) be within a certain range of values. Insome designs, the ratio of the heights of the real space peaks for thefirst and second coordination sphere in suitable carbons (e.g., ascomponents of suitable carbon-containing electrode composites) maypreferably range from around 0.700 to around 0.590 (in some designs,from around 0.700 to around 0.650; in other designs, from around 0.650to around 0.620; in yet other example, from around 0.620 to around0.590, depending on the composite particle chemistry, microstructure,and electrode operation conditions). Such Synchrotron XRD measurementsand PDF analysis may be conducted either on the carbon materials (e.g.,to select proper synthesis/processing conditions) or on thecarbon-containing composites (e.g., with Si-based and/or Si-comprisingactive material, among others) (e.g., to detect the presence orretention of suitable carbon in the composites).

For a perfectly ordered crystalline graphite, the ratio of the FWHMvalues for the first and the second coordination spheres should be 1. Insome artificial graphite samples with significant degrees of disorder,such values may be smaller, such as in the range from around 0.850 toaround 0.950. However, in some designs, in suitable carbons the ratio ofFWHM values may preferably be even smaller (which is related to thecertain degree of variations in bond lengths and disorder that benefitcarbon performance in composites and may potentially be related tovarious distortions, such as vacancies, off-membered rings, etc.). Insome designs, the ratio the FWHM values for the first and secondcoordination sphere in suitable carbons may preferably range from around0.700 to around 0.850 (in some designs, from around 0.700 to around0.760; in other designs, from around 0.760 to around 0.810; in yet otherdesigns, from around 0.810 to around 0.830; in yet other designs, fromaround 0.830 to around 0.850), depending on the composite electrodeparticle active material and composition and electrode operationalconditions, among other factors. Such Synchrotron XRD measurements andPDF analysis may be conducted either on the carbon materials (e.g., toselect proper synthesis/processing conditions) or on thecarbon-containing composites (e.g., with Si-based and/or Si-comprisingactive material, among others) (e.g., to detect the presence orretention of suitable carbon in the composites).

In case of a perfect crystalline graphite, the ratio of the heights ofthe real space peaks for the first and third coordination sphere shouldbe 1. However, in some designs, in suitable carbons the ratio of theheights of the real space peaks for the first and third coordinationsphere may preferably be larger (which may be related to certaindisorders that benefit carbon performance in composites and maypotentially be related to various distortions, such as vacancies,off-membered rings, etc.). In some designs, the ratio of the heights ofthe real space peaks for the first and the third coordination sphere insuitable carbons should preferably range from around to around 1.100 toaround 1.300 (in some designs, from around 1.100 to around 1.150; inother designs, from around 1.150 to around 1.180; in yet other designs,from around 1.180 to around 1.240; in yet other designs, from around1.240 to around 1.300), depending on the composite electrode particleactive material and composition and electrode operational conditions,among other factors. Such Synchrotron XRD measurements and PDF analysismay be conducted either on the carbon materials (e.g., to select propersynthesis/processing conditions) or on the carbon-containing composites(e.g., with Si-based and/or Si-comprising active material, among others)(e.g., to detect the presence or retention of suitable carbon in thecomposites).

For a perfectly ordered crystalline graphite, the ratio of the FWHMvalues for the first and the third coordination spheres should be 1.However, in suitable carbons the ratio of FWHM values may preferably beeven smaller (which is related to the certain degree of variations inbond lengths and disorder that benefit carbon performance in compositesand may potentially be related to various distortions, such asvacancies, off-membered rings, etc.). In some designs, the ratio of theFWHM values for the first and the third coordination sphere in suitablecarbons may preferably range from around 0.600 to around 0.850 (in somedesigns, from around 0.600 to around 0.700; in some designs, from around0.700 to around 0.760; in other designs, from around 0.760 to around0.810; in yet other designs, from around 0.810 to around 0.830; in yetother designs, from around 0.830 to around 0.850), depending on thecomposite electrode particle active material and composition andelectrode operational conditions, among other factors. Such SynchrotronXRD measurements and PDF analysis may be conducted either on the carbonmaterials (e.g., to select proper synthesis/processing conditions) or onthe carbon-containing composites (e.g., with Si-based and/orSi-comprising active material, among others) (e.g., to detect thepresence or retention of suitable carbon in the composites).

FIG. 9A shows illustrative examples of structural properties forsuitable carbons (e.g., porous carbons in this example) that may be usedin the formation of suitable, high-performance carbon-containingelectrode composites (e.g., with Si-based and/or Si-comprising activematerial). In such illustrative examples, the ratio of the heights ofthe real space peaks for the first and the second coordination sphere insuitable carbons are: 0.660, 0.625, 0.596 and 0.595. Lower value of theratio indicates a higher degree of order in the suitable carbons'examples. An inset at the top of FIG. 9A shows a 5-membered ring, a6-membered ring, and a 7-membered ring. Arrow lines schematicallyrepresenting the second and third coordination spheres in the case ofthe six-membered rings are shown. It will be appreciated that the secondand third coordination spheres (as well as the first coordination sphereand higher-order coordination spheres) would be altered in the case ofthe five-membered and seven-membered rings.

FIG. 9B shows illustrative examples of structural properties for thesuitable (e.g., porous carbons in this example) that may be used in theformation of suitable, high-performance carbon-containing electrodecomposites (e.g., with Si-based and/or Si-comprising active material).In such illustrative examples, the ratio of the FWHM values for thefirst and the second coordination sphere in suitable carbons are 0.773,0.771, 0.795, 0.814 and 0.830.

FIG. 9C shows illustrative examples of structural properties for thesuitable carbons (e.g., porous carbons in this example) that may be usedin the formation of suitable, high-performance carbon-containingelectrode composites (e.g., with Si-based and/or Si-comprising activematerial). In such illustrative examples, the ratio of the heights ofthe real space peaks for the first and the third coordination sphere insuitable carbons: are 1.237, 1.210, 1.194 and 1.230.

FIG. 9D shows illustrative examples of structural properties for thesuitable carbons (e.g., porous carbons in this example) that may be usedin the formation of suitable, high-performance carbon-containingelectrode composites (e.g., with Si-based and/or Si-comprising activematerial). In such illustrative examples, the ratio of the FWHM valuesfor the first and the second coordination sphere in suitable carbons are0.657, 0.625, 0.650, 0.695, 0.839.

Unexpectedly, certain values of the relative intensities of the C—Cbonds in the first coordination sphere in the radial distributionfunction, R(r), with that of bonds between C and active materials (e.g.,Si in the case of Si-based anodes for Li-ion batteries, such as Si—Cbonds) may correlate with the performance of carbon-containing andactive material-containing composites. As such, processing conditionsfor the formation of such carbon-containing composites may be optimized.In a crystalline SiC the first atom-atom (Si—C) pair is located ataround r=1.9 Å. In a crystalline graphite (and many graphitic carbons,even if disordered) the first carbon atom-atom (C—C) pair is located ataround r=1.42 Å and the second C—C bond is found at around r=2.47 Å. Ina crystalline Si the first atom-atom (Si—Si) pair bond is located ataround r=2.37 Å, which is close to the second C—C bond in graphiticcarbon. In composites that comprise both carbon (C) and Si, theintensities of the corresponding peaks in R(r) may be used forperformance optimization. However, the first Si—Si bond distanceoverlaps with the second C—C bond distance. In some designs ofcomposites comprising both Si and C, the ratio of the intensity of thefirst Si—C pair bond to that of the first C—C pair bond in R(r) shouldpreferably range from around 0.050 to around 1.000 (in some designs,from around 0.050 to around 0.350; in other designs, from around 0.350to around 0.700; in yet other designs, from around 0.700 to around1.000). Too large intensity ratio (e.g., substantially above 1.000, suchas 1.25 or 1.95, in some examples) may typically lead to significantlyinferior performance in cells (e.g., lower capacity, stability, rateperformance, etc.). In general, lower intensity ratio values (reducedSi—C bond formation) may often be preferable; however, too smallintensity ratio (e.g., substantially below around 0.050) may also reducesome aspects of performance (e.g., first cycle efficiency, stability,etc.). While the first coordination sphere of silicon (at around r=2.37Å) and the second one of graphitic carbon (at around r=2.47 Å) areconvoluted with each other, the position of the real space peak maximumof this convoluted peak in the composites comprising both Si and C mayalso be used for the performance optimization during tuning of thesynthesis/processing conditions. For example, in some designs, it may bepreferable for the position of maximum of this convoluted peak to rangefrom around 2.375 Å to around 2.425 Å (in some designs, from around2.375 Å to around 2.395 Å; in other designs, from around 2.395 Å toaround 2.405 Å; in yet other designs, from around 2.405 Å to around2.425 Å). The ratio of the intensity of the convoluted (first Si—Si andsecond C—C) to that of the first C—C peak should preferably be alsowithin a certain range for optimum performance of the carbon-basedcomposites with Si as active material. In some designs, it may bepreferable for the ratio of such intensities to range from around 1.500to around 6.500 (in some designs, from around 1.500 to around 3.000; inother designs, from around 3.000 to around 4.500; in yet other designs,from around 4.500 to around 6.500).

FIG. 10 illustrates examples of the G(r) of illustrative suitablecarbon-containing composites that comprise Si as active material. Inthese particular examples, the ratio of the intensity of the first Si—Cpair bond to that of the first C—C pair bond in R(r) is around 0.642 and0.522, respectively (with the example having 0.522 offering slightlysuperior performance). In these particular examples, the positions ofmaximum of the (first Si—Si and second C—C) convoluted peaks are aroundr=2.391 Å and r=2.385 Å, respectively (with the example having r=2.385 Åoffering slightly superior performance). In these particular examples,ratio of the intensity of the convoluted (first Si—Si and second C—C) tothat of the first C—C peak are around 3.333 and 3.363, respectively(with the example having 3.363 peak intensity ratio offering slightlysuperior performance).

In some designs, it may be advantageous (for various performancecharacteristics) for the carbon-containing composites (e.g., compositeparticles) to exhibit a certain spectral signature detected in Ramanspectroscopy studies. In particular, in some designs, it may beadvantageous for the ratio of intensities of the carbon D band andcarbon G band (I_(D)/I_(G)) in the Raman spectra of the majority (e.g.,about 50-100 wt. %) of composite particles (measured, for example, usingthe laser wavelength of about 532 nm; and analyzed, for example, in thespectral wavenumber range from about 1000 to about 2000 cm⁻¹ by fittingtwo Gaussian peaks after a linear background subtraction in this range)to range from I_(D)/I_(G) of about 0.7 to I_(D)/I_(G) of about 2.7 (insome designs, from about 0.9 to about 2.1). Note that these ranges usethe ratio of the absolute intensities of the D and G peaks (obtained byfitting the spectra by two G peaks and two D peaks using Gaussian modelsand using the intensities/heights of the tallest G peak and the tallestD peak), and not the ratio of the integrated intensities (areas undereach of the D and G peaks). However, in some designs, it may beadvantageous for the ratio of the integrated intensities of the D peakto G peak (areas under the corresponding peaks) (obtained by fitting thespectra by two G peaks and two D peaks using Gaussian models,calculating the sum of the areas under both Gaussian model G peaks(I_(G total area)), calculating the sum of the areas under both Gaussianmodel D peaks (I_(D total area)) and calculating the ratio of these twosums: I_(D total area)/I_(G total area)) to range from about 0.7 toabout 2.7 (or 4, in some designs).

In some designs, it may be advantageous for the full width at halfmaximum (FWHM) of the carbon G band in the Raman spectra of the majorityof carbon-containing composite particles (measured, for example, usingthe laser wavelength of about 532 nm; and analyzed, for example, in thespectral wavenumber range from about 1000 to about 2000 cm⁻¹ by fittingtwo Gaussian peaks after a linear background subtraction in this range)to range from about 10 cm⁻¹ to about 150 cm⁻¹ (in some designs, fromabout 50 cm⁻¹ to about 100 cm⁻¹).

In some designs, the sources of carbon for the formation of suitablecarbon-containing composites may include, but are not limited to: (i)various carbon-containing gases (e.g., various hydrocarbon (e.g., C₅H₁₂,C₅H₁₀, C₅H₈, C₆H₆, etc.) vapors; hydrocarbon gases (e.g., CH₄, C₂H₂,C₂H₄, C₂H₆, C₃H₆, C₃H₈, C₃H₄, C₄H₁₀, C₄H₈, C₄H₆, etc.), among others ortheir combinations), (ii) various carbon-containing liquids (e.g.,solutions of monosaccharides, disaccharides and polysaccharides such asglucose, fructose, galactose, ribose, deoxyribose, sucrose, lactose,maltose, starch, alginate, amylose, amylopectin, glycogen, lignin, amongothers), crude oil, coal tar pitch, petroleum pitch, bio-pitch and theirvarious solutions, plant-derived oils, propane, butane, ethane, variousolefins and many other liquid hydrocarbons) and (iii) variouscarbon-containing solids (e.g., various nut shells (e.g., coconutshells, apricot shells, almond shells, among others), various pits(e.g., olive pits, cherry stone, apricot stone, peach stone, avocadostone, among others), various wood and wood waste products (e.g., sawdust), bamboo, grass/straw and (dry) leaves (e.g., banana fibers, ricehusk, corncob, kelp, among others), coal and various saccharides andsaccharide-comprising natural compounds, including monosaccharides,disaccharides and polysaccharides (glucose, fructose, galactose, ribose,deoxyribose, sucrose, lactose, maltose, starch, gum arabic, lignin,cellulose, chitin, alginate, amylose, amylopectin, glycogen, amongothers), various human wastes, various food processing wastes and foodwastes, wastepaper products, various polymers (e.g., naturalglycoproteins and their mixtures, phenolic and furfural resins includingpoly(furfuryl alcohol), rayon, polyethylene, polypropylene, nylons,polyurethanes, polylactide, polyglycolide, polyamides, polyaramids,polyethylene terephthalate, polyacrylonitrile, poly(p-phenylenevinylene), various polyoxymethylenes, various vinyl polymers, among manyother known carbon polymer precursors)) and their various combinations,various metal (e.g., Mg, Al, Si, Zn, Sn, Sb, or Ti, etc.) or ammonium(NH₃) salts of various organic acids (e.g., lactic acid, acetic acid,formic acid, citric acid, oxalic acid, uric acid, malic acid, tartaricacid, carboxylic acids, etc.) or various organic acids (e.g., lacticacid, acetic acid, formic acid, citric acid, oxalic acid, uric acid,malic acid, tartaric acid, carboxylic acids, etc.) and theircombinations, to provide a few illustrative examples. In some designs,inorganic residues (e.g., oxides or others) produced by (e.g., thermal)decomposition of some of such carbon precursors or carbon-comprisingprecursors (by carbonization) may be dissolved in (e.g., mild) acids orbases or, in some designs, converted to active material (e.g., Si) byknown means (e.g., by magnesiothermic reduction of silicon oxideresidues followed by dissolution of magnesium oxide or other suitablemeans).

In some designs, carbon comprising composite particles may be producedby first producing porous carbon and then infiltrating the pores withintercalation-type or conversion-type (including alloying-type) activematerials. In some designs, such an infiltration process may beconducted by using vapor deposition techniques (such as CVD, atomiclayer deposition (ALD), among others) or solution infiltrationtechniques (including a sol-gel or hydrothermal synthesis orlayer-by-layer deposition or electrodeposition or electroless depositionor electrophoretic deposition or salt infiltration followed by solventevaporation and decomposition or conversion in a controlled environment,among others) or melt-infiltration (e.g., infiltrating a precursor or acomponent of a precursor from a melt) or various combination(s) of morethan one of such techniques (e.g., an infiltration of a precursor (e.g.,inorganic or metal-organic or organometallic, etc.) salt(s) fromsolution or vapor phases or melt followed by annealing or heat-treatmentin controlled gaseous environment—reducing (e.g., in H₂ orhydrogen-containing gases such as hydrocarbon gases or vapors, amongothers) or oxidizing (e.g., in O or F or Cl or S containing gases, amongothers) or neutral (e.g., as N₂ or Ar or He gases or vacuum), where thegaseous environment may comprise molecules comprising fluorine orhydrogen or oxygen or sulfur or phosphorous or lithium or sodium orpotassium or calcium atoms, etc.). As such, in some designs, precursorsmay first be infiltrated and then converted to suitableintercalation-type or psuodocapacitive-type active materials by, forexample, heat-treatment under a suitable gaseous (or vaporous)environment.

In some designs, as previously mentioned, an additional shelling (orpore-plugging) material layer may at least partially enclose (or coat)active materials, carbon or the whole composite particles. The maximumheat-treatment (e.g., in a controlled environment) temperature of suchprocesses during the composite formation may vary depending on compositeproperties and composition of the intercalation-type active material(e.g., its thermal stability, mobility, reactivity in contact withcarbon, etc.), but in some designs may be in a range from around 100° C.to around 1,100° C. (sometimes, from around 300 to around 800° C.). Insome designs, more than one heat-treatment in different gaseousenvironments (e.g., initially in O- or F-containing and then in Ar orN₂) at different temperatures (e.g., from around 50° C. to around 1,100°C.) or pressures (e.g., from around 0.0001 Torr to 20,000 Torr; in somedesigns—near atmospheric pressure) and/or for different time durations(e.g., from around 0.0001 sec to around 240 hours) may be implemented totune material synthesis (e.g., for the formation of composites with adesired active particle size residing primarily within the carbon poresand with a desired phase and stoichiometry of active material particles,etc.).

In some designs, synthesis of carbon-containing composites may involvemixing carbon powders (e.g., exfoliated carbon, graphene, activatedcarbon, carbon black, dendritic carbon, carbon nanotubes, etc.) withorganic carbon precursors (e.g., starch, various sugars, cellulose andcellulose-derived products, alginate and alginate-derived products,pitch (e.g., mesophase pitch, plant-derived pitch, coal tar pitch, etc.)and its various components, coal, coal tar, lignins, gum arabic, variousother polysaccharides, natural glycoproteins and their mixtures,phenolic and furfural resins including poly(furfuryl alcohol), ayon,polyethylene, polyacrylonitrile, poly(p-phenylene vinylene), variousvinyl polymers, among many other known carbon precursors) and activematerial (nano)particles (e.g., silicon or silicon oxide or nitride incase of the formation of Si-based composites as illustrative example) oractive material precursor (e.g., oxides and other salts; including saltsolutions) (either in a dry state or in a solution/suspension) andcarbonize such a mixture to obtain carbon-containing composites. In somedesigns, such mixtures may comprise just organic carbon precursors(e.g., polymers) and active material (or active material precursor)(without carbon particles). In an example, the temperature of thecarbonization (pyrolysis) or the subsequent (e.g., to spraying orparticle formation) heat treatment may vary depending on the activematerial composition and may range from around 300° C. to around 1200°C. (in some designs, from around 450° C. to around 1000° C.). In somedesigns, higher temperatures may lead to the undesirable reaction ofactive material or active material with carbon forming carbides andother undesirable compositions. In some designs, lower temperatures maylimit rate performance and capacity of the produced composites.

In some designs, it may be advantageous to utilize a spray-dryingtechnique or a spray pyrolysis technique as at least one of the stagesin composite synthesis. In some designs, it may be advantageous toutilize hydrothermal (or solvothermal) treatment during at least one ofthe stages in composite synthesis (e.g., to induce oxidation orcrystallization of the precursor at relatively low temperatures withoutburning/over-oxidizing carbon, etc.). In some designs, it may beadvantageous to utilize hydrothermal treatment in combination withheat-treatment in a controlled environment (e.g., a reactive environmentsuch as oxygen-containing or fluorine-containing at low temperatures(e.g., from around room temperature to around 350-400° C.) or inert athigher temperatures (e.g., from around 400° C. to around 600-1200° C.,depending on a particular chemistry and its stability of active materialin contact with carbon) or both).

In some designs, thus produced carbon/active material compositeparticles may be at least partially milled to produce the desiredparticle size distribution.

In some designs, thus produced carbon/active material compositeparticles may be further (at least partially) enclosed in a functionalshelling (or pore-plugging) layer (e.g., to enhance electricalconductivity or to enhance ionic conductivity or to enhance wetting byelectrolyte or to prevent undesirable interactions between electrolyteand active material or for other advantageous purposes). In somedesigns, the shelling material layer may preferentially coat either theactive material or the carbon walls (e.g., by having different wettingor different nucleating time on the carbon surface vs. that of theactive material). In some designs, the volume fraction of the functionalshelling layer may range from around 0.001 vol. % to around 20 vol. % ofthe volume of the composite particles. In some designs, the functionalshelling material layer may also act as “active” material in terms ofits ion storage capability (e.g., exhibit capacity in the range fromaround 0.1% to around 75% of that of the active material when expressedin the units of capacity per unit mass, mAh/g, or capacity per unitvolume, mAh/cc). In some designs, such a shelling material layer may bedeposited by using vapor deposition techniques (such as CVD, ALD, amongothers), electrochemical deposition, electrodeposition, electrolessdeposition, electrophoretic deposition, layer-by-layer deposition orvarious other solution-based deposition techniques or combination ofboth solution and vapor depositions. In some designs, after the shellingmaterial deposition, the composite may be heat-treated (e.g., attemperatures from around 100 to around 1000° C.) in a suitable gaseousenvironment (e.g., inert gas, such as N₂ or Ar or He, among others) orvacuum to enhance composite properties. In some designs, the averagethickness of the shelling material layer may vary depending on theparticle size, ionic and electrical conductivity of such a layer and/orother properties. In some designs, a suitable thickness (e.g., averagethickness) of the shelling material layer may range from around 0.2 nmto around 200 nm, although a larger thickness may also be acceptable insome applications (although possibly at the expense of reducedvolumetric capacity of the electrodes or reduced electrode porosity). Insome designs, the shelling material layer may comprise carbon (C) (e.g.,in some designs, mostly conductive sp²-bonded carbon, as in graphite orgraphitic carbon or turbostratic carbons or most amorphous carbons). Insome designs, various carbon atoms comprising solvents or varioushydrocarbon (e.g., C₅H₁₂, C₅H₁₀, C₅H₈, C₆H₆, etc.) vapors may be used asprecursors for carbon deposition. In some designs, hydrocarbon gases(e.g., CH₄, C₂H₂, C₂H₄, C₂H₆, C₃H₆, C₃H₈, C₃H₄, C₄H₁₀, C₄H₈, C₄H₆, etc.)or their combinations may advantageously be used as precursors forcarbon deposition. In some designs, viscoelastic polymers (includingbio-derived ones, such as pitch) may be used as precursors for carbonlayer formation. In some designs, the pitch may be derived frompetroleum, coal tar, plants (including wood). In some designs, theshelling material layer may be a composite of two more materials. Insome designs, the shelling material may comprise flake-shaped particles.In some designs, the shelling material may comprise one or more of thefollowing elements: transition, alkali or alkaline-earth metal (such asiron (Fe), manganese (Mn), copper (Cu), yittrium (Y), zirconium (Zr),niobium (Nb), molybdenum (Mo), chromium (Cr), lithium (Li), sodium (Na),magnesium (Mg), potassium (K), calcium (Ca), strontium (Sr), cesium(Cs), barium (Ba), among others), lanthanum or lanthanoids (La, Ce, Gd,Nd, Eu, etc.), beryllium (Be), aluminum (Al), silicon (Si), gallium(Ga), germanium (Ge), phosphorous (P), arsenic (As), tin (Sn), bismuth(Bi), lead (Pb), indium (In), cadmium (Cd), zinc (Zn), fluorine (F),iodine (I), oxygen (O), nitrogen (N), sulfur (S), selenium (Se),tellurium (Te), hydrogen (H) and carbon (C). In some designs, theshelling material layer may comprise a polymer. In some designs, apolymer used in the shelling material layer may exhibit high electricaland/or ionic conductivity (e.g., in the range from around 10⁻⁷ to around10⁻⁴ S/cm). In some designs, a polymer layer in the shelling materiallayer may be at least partially carbonized. In some designs, theshelling material layer may comprise a glass or ceramic layer. In somedesigns, a glass or ceramic layer may exhibit high electrical and/orionic conductivity (e.g., in the range from around 10⁻⁷ to around 10⁺⁴S/cm). In some designs, the shelling material layer may comprise a metalor metal alloy.

In some designs, formation of suitable porous carbons may involvecarbonization (e.g., by thermal annealing or by hydrothermal treatmentor by other means) of a suitable organic precursor followed by chemicalor physical activation and/or dissolution or conversion of inorganicresidues. In some designs, formation of so-called hydrochars (carbonsproduced by hydrothermal treatment of the hydrocarbon precursors) may beadvantageous relative to other carbonization techniques due to highcarbon conversion efficiency, uniform distribution of oxygen in thematerial and other favorable characteristics. Suitable examples of thehydrochar precursors include, but are not limited to various nut shells(e.g., coconut shells, apricot shells, almond shells, among others),various pits (e.g., olive pits, cherry stone, apricot stone, peachstone, avocado stone, among others), various wood and wood wasteproducts (e.g., saw dust), bamboo, grass/straw and (dry) leaves (e.g.,banana fibers, rice husk, corncob, kelp, among others), various humanwastes, various food processing wastes and food wastes, waste paperproducts, coal and coal tar pitch, petroleum pitch, crude oil, varioussaccharides, including monosaccharides, disaccharides andpolysaccharides (glucose, fructose, galactose, ribose, deoxyribose,sucrose, lactose, maltose, starch, lignin, cellulose, amylose,amylopectin, glycogen, among other suitable precursors). In somedesigns, hydrochars may be annealed in an inert environment (e.g., invacuum or in N₂ or Ar or He gas, etc.) prior to (e.g., the first)activation. Suitable temperatures may range from around 500° C. toaround 2000° C., depending on the precursor and the desired porosityafter activation. In some designs, heat-treatment at temperatures lowerthan around 500° C. may have little impact on activation and may notremove (a desired) amount of impurities (e.g., as effluent(s)). In somedesigns, heat-treatment at temperatures higher than around 2000° C. isvery effective in obtaining high-purity material but may prevent onefrom achieving high BET SSA and retaining (sometimes desirable) smallpores after activation.

In some designs, it may be advantageous to use so-called physicalactivation techniques (such as activation in a stream of CO₂ or H₂O orboth, among others) to induce additional pores and increase pore volumeand surface area of carbons produced by carbonization. Suitableactivation temperature may vary depending on the types of the carbonsand pre-treatment history. However, as an example, suitable temperaturesmay be in the range from around 700° C. to around 1300° C. (in somedesigns—from around 800 to around 1150° C.). In an example, temperatureshigher than around 1300° C. may make the activation process verydifficult to control to a desired uniformity and may additionally induceundesirable pore size distribution within carbon. In another example,temperatures lower than around 700° C. may make the activation processtoo slow and may not achieve the desired pore size and surface areacharacteristics in the produced activated carbon.

In some designs, formation of suitable porous carbons (e.g., whenattaining a larger pore volume) may involve the use of sacrificialtemplate materials prior to carbonization and activation.

In some designs, formation of so-called hydrochars (carbons produced byhydrothermal treatment of the hydrocarbon precursors, including variousbiomaterials, such as shells, wood wastes, etc.) may be advantageousprior to activation.

In some designs, carbon precursors may be annealed in an inertenvironment (e.g., in vacuum or in N₂ or Ar or He gas, etc.) prior toactivation. In some designs, suitable temperatures may range from around500° C. to around 2800° C. (in some designs, from around 500° C. toaround 800° C.; in other designs, from around 800° C. to around 1200°C.; in yet other designs, from around 1200° C. to around 1600° C.; inyet other designs, from around 1600° C. to around 2000° C.; in yet otherdesigns, from around 2000° C. to around 2800° C.), depending on theprecursor and the desired porosity after activation. In some designs,heat-treatment at temperatures lower than around 500° C. may have toolittle impact on activation and may not remove (a sometimes desired)amount of impurities (e.g., as effluent(s)). In some designs,heat-treatment at temperatures higher than around 2800° C. is veryeffective in obtaining high-purity material, but may prevent one fromachieving high BET SSA and forming (sometimes desirable) small poresafter activation.

In some designs, chemical activation may be used instead or in additionto physical activation. Examples of suitable chemical activation agentsinclude, but are not limited to, KOH, NaOH, ZnCl₂, H₃PO₄, K₂CO₃, orH₂SO₄. In some designs, the carbonization stage proceeds concurrentlywith the chemical activation. In other designs, after carbonizing theprecursor, the obtained carbon may then be mixed with chemicalactivation agent, heat-treated for activation and then purified.

In some designs (e.g., to maximize rate performance or batterystability), porous carbon may be annealed in an inert environment (e.g.,in vacuum or in N₂ or Ar or He gas, etc.) after the activation. Theannealing process may provide additional purification, may enhanceelectrical conductivity of carbon, may enhance mechanical properties ofcarbon, may reduce the number of nucleation cites (for deposition ofactive materials) and may lead to reduced self-discharge and otherperformance benefits in cells (e.g., better rate, better stability,etc.). In some designs, suitable temperatures may range from around 800°C. to around 2800° C. (in some designs, from around 800° C. to around1200° C.; in yet other designs, from around 1200° C. to around 1400° C.;in yet other designs, from around 1400° C. to around 1800° C.; in yetother designs, from around 1800° C. to around 2800° C.), depending onthe precursor and the desired porosity after activation. In somedesigns, heat-treatment at temperatures lower than around 800° C. mayhave too little impact on infiltration of active materials into theporous structure or bonding of active material with carbon or carbonconductivity or purity. In some designs, heat-treatment at temperatureshigher than around 2800° C. may prevent one from achieving high BET SSAand induce excessive pore closer after the activation.

In some designs, porous carbons may be annealed and activated more thanonce (e.g., two or three or more times) in order to attain the mostdesirable characteristics for use in carbon-containing electrodecomposites. In some designs, different thermal treatment (annealing)temperatures may be intentionally used prior to the different activationprocedures.

In some designs, it may be advantageous for the electrodes comprisingconversion-type (including alloying-type or metal-type) active materialsor intercalation-type or pseudocapacitive-type active materials to beprepared in certain ways or to comprise certain conductive or otheradditives.

In some designs, it may be advantageous to use nanoparticles (e.g.,carbon black, including those that comprise linked carbon particles intolarger agglomerates) or one dimensional (1D) conductive additives (suchas single-walled carbon nanotubes, double-walled carbon nanotubes,multiwall carbon nanotubes, carbon (nano)fibers, compatible metalnanofibers, nanotubes and nanowires (e.g., copper, nickel, titanium,iron nanowires/nanofibers, aluminum nanowires/nanofibers, nickelnanowires/nanofibers, etc.)) or their combination in electrodescomprising the carbon containing composite electrode materials.

In some designs, it may be advantageous to attach conductive additivesto the (nano)composite electrode particles by some mechanisms. In oneexample, conductive additives (e.g., carbon nanotubes or graphene ormetal nanoparticles or metal nanowires) may be directly on the surfaceof the electrode particles (e.g., by CVD or by solution chemistryroutes). In another example, the conductive particles (of various shapesand sizes) may be strongly attached to the surface of the electrodeparticles by making the surface of each (or most) particle(s) chargedand by using the opposite charge on the electrode particles vs.conductive additive particles. In yet another example, the conductiveparticles may be attached to the surface of the electrode particlesusing an organic (e.g., a polymer) binder and by carbonizing the binderforming a conductive carbon interlayer (e.g., which effectively acts asa conductive glue) between the conductive additive(s) and the electrodeparticle(s). In yet another example, one may CVD deposit a carbon layeron the mixture of conductive additive particles and active electrodeparticles, thereby preferentially depositing carbon at the contactpoints between the electrode particles and conductive additives. In anexample, the CVD carbon layer may similarly act as a conductive glue tostrongly attach conductive additive(s) to the electrode particle(s).

In some designs, the optimal wt. % of slurry components, given as aratio of the mass of non-active components to the external surface areaof composite electrode particles, may exhibit values ranging from around1 to around 5,000 m² active/g non-actives (e.g., from around 5 to around200 m² active/g non-actives). In some designs, the optimal wt. % ofslurry components for a particular electrode composition may depend onthe size of the active particles, type of conductive additives, surfacechemistry of the conductive additives, surface chemistry of the activeparticles, density of the particles, volume changes during cycling, typeand molecular weight of the binder(s), thickness of the electrode,density of the electrode and/or other parameters.

In some applications, it may be advantageous to induce an oppositecharge on the surface of conductive additives and the (composite)electrode particles in order to enhance their contact area and contactstrength and achieve more uniform mixing. For example, a positive chargemay be introduced on the surface of the composite particles and anegative charge may be introduced on the surface of conductiveadditives. In another example, a negative charge may be introduced onthe surface of the composite particles and a positive charge may beintroduced on the surface of conductive additives. In some applications,it may be advantageous to induce a chemical reaction between conductiveadditives and the electrode particles during or after electrode drying.

In some designs, it may be advantageous to use more than one type ofconductive additive (e.g., having different dimensions, aspect ratio ormorphology) for most optimal performance. In some designs, it may befurther advantageous to chemically bond one type of conductive additiveto the surface of electrode particles. In this case, as an example, therequirements on the lack of swelling for maintaining stability of theelectrode particle/conductive additive interface may be substantiallyreduced or even completely avoided. In one example, short (e.g., around0.01-10 micron) carbon nanofibers, carbon nanotubes, orgraphene/graphite ribbons may be grown from the surface of electrodeparticles (e.g., by using catalyst-assisted chemical vapor deposition,CVD, or other mechanisms). In another example, a mixture of conductivecarbon additive particles (e.g., carbon black, carbon nanotubes, etc.)with one charge and electrode particles with the opposite charge may beadditionally mixed with a small sacrificial binder content and thencarbonized. In some designs, the carbonized binder may firmly andpermanently attach some of the carbon additives to the surface of theelectrode particles. In an example, such electrode particles/carbonadditives composites may be used in slurries with various suitablebinders and additional conductive additives to form (or cast) morestable electrodes that experience moderate volume changes during cycling(e.g., as applicable in the context of one or more embodiments of thepresent disclosure).

In some applications, it may be advantageous to use two or moreconductive additives with different surface charges or different surfacechemistries. In particular, in some designs, when one type of additiveexhibits higher affinity to the electrode particles, such an additivemay be selected to form a uniform coating around the electrodeparticles. In some designs, such an additive may also be selected toform chemical bonds with the electrode particles at some stage of theelectrode assembling or slurry preparation. As an example, the secondadditive may be incorporated into the binder in significantly higherfraction than the first additive and thus be optimized for formingrobust and uniform binder/additive (nano)composites that yield stableelectrodes.

In some applications, two or more conductive additives may be selectedto achieve different functions. In one example, one type of additive(e.g., with larger dimensions or higher conductivity, such as carbonnanofibers, other conductive nanofibers, long (e.g., above around 10micron in length) carbon nanotubes, graphite or graphene flakes withlinear dimensions in excess of around 5-10 micron, other conductiveflakes, metal nanowires, etc.) may be selected to provide higherelectrical conductivity within the electrode as a whole, while thesecond type of conductive additive (e.g., carbon black and otherconductive nanoparticles, shorter (e.g., around 0.25-10 micron inaverage length) carbon nanotubes or conductive nanowires or (e.g.,chopped) conductive nanofibers, smaller graphene or graphite flakes,shorter graphite ribbons, etc.) may be selected to ensure that eachindividual electrode particle is effectively electrically connected tomultiple neighboring electrode particles and the first type of additive,thereby forming an efficient conductive network that results in highcapacity utilization of the electrode material. In another example onetype of additive may be selected to perform multiple functions (e.g., toenhance both electrical conductivity and mechanical stability of theelectrodes or to enhance electrical conductivity of the electrode andprovide faster ionic pathways (e.g., if it is porous or if it preventselectrode pore closing)). In some designs, one type of conductiveadditive may also assist in better dispersing the second type during theslurry mixing. In particular, in some designs, it may be advantageous touse a mixture of two of the following types of conductive additives inthe same slurry: (i) various types of single walled carbon nanotubes(SWCNTs) (with or without surface coatings); (ii) various types ofdouble-walled (DWCNTs), triple-walled (TWCNTs) and other types ofmultiwalled carbon nanotubes (MWCNTs) (with or without surfacecoatings); (iii) various types of carbon black (including those that areannealed at above 1000° C. in inert environment); (iv) various types ofcarbon fibers (including those that are annealed at above 1000° C. in aninert environment); (v) various types of carbon nanofibers; (vi) varioustypes of metal nanowires (without or with protective or functionalsurface coating layers) (e.g., Cu, Fe, Ti, or Ni nanowires for lowpotential anodes in Li-ion batteries, such as Si comprising anodes; Alnanowires for cathodes or high voltage anodes in Li-ion batteries, orother nanowires (e.g., Ni or Ti nanowires) for various aqueousbatteries, etc.); (vii) various types of carbon-coated or metal- (e.g.,Cu, Fe, Ni, Ti or Al, etc.) coated ceramic nanowires or fibers (e.g.,Al₂O₃ nanowires or fibers); (viii) various types of carbon onions; (ix)various types of graphite ribbons (including metal-coated graphiteribbons); (x) various types of metal (e.g., Cu, Fe, Ni, Ti or Al, etc.)nanoparticles (with or without coatings by a protective or functionalsurface layer); and (xi) various types of metal (e.g., Cu, Fe, Ni, Ti orAl, etc.) (nano)flakes (with or without coatings by a protective orfunctional surface layer), to name a few examples. In some designs, thesurface chemistry of each type of such additive could be individuallyoptimized for optimum performance in cells.

In some applications, it may be advantageous to restrict the overallvolume fraction of all conductive additive particles within theelectrode to less than around 5 vol. % (even more preferably belowaround 2 vol. %). In some designs, by mass, the fraction of allconductive additive particles within the electrode may preferably beless than around 7 wt. % (e.g., even more preferably below around 3 wt.%) if only carbon materials are used as conductive additives and lessthan around 10 wt. % (e.g., even more preferably below around 5 wt. %)if some of the conductive additives comprise suitable metals. In anexample, a higher volume fraction of conductive additives may reduceionic transport and volumetric capacity of electrodes and may increasethe extent of undesirable side reactions. In a further example, a highergravimetric (mass) fraction of conductive additives may reduce thespecific capacity of the electrodes.

In the detailed description above it can be seen that different featuresare grouped together in examples. This manner of disclosure should notbe understood as an intention that the example clauses have morefeatures than are explicitly mentioned in each clause. Rather, thevarious aspects of the disclosure may include fewer than all features ofan individual example clause disclosed. Therefore, the following clausesshould hereby be deemed to be incorporated in the description, whereineach clause by itself can stand as a separate example. Although eachdependent clause can refer in the clauses to a specific combination withone of the other clauses, the aspect(s) of that dependent clause are notlimited to the specific combination. It will be appreciated that otherexample clauses can also include a combination of the dependent clauseaspect(s) with the subject matter of any other dependent clause orindependent clause or a combination of any feature with other dependentand independent clauses. The various aspects disclosed herein expresslyinclude these combinations, unless it is explicitly expressed or can bereadily inferred that a specific combination is not intended (e.g.,contradictory aspects, such as defining an element as both an electricalinsulator and an electrical conductor). Furthermore, it is also intendedthat aspects of a clause can be included in any other independentclause, even if the clause is not directly dependent on the independentclause.

Implementation examples are described in the following numbered clauses:

Clause 1. A lithium-ion battery anode composition, comprising: a porouscomposite particle comprising carbon (C) and an active materialcomprising silicon (Si), wherein the carbon is characterized by a domainsize (r), as estimated from an atomic pair distribution function G(r)obtained from a synchrotron x-ray diffraction measurement of the porouscomposite particle, ranging from around 10 Å (1 nm) to around 60 Å (6nm).

Clause 2. The lithium-ion battery anode composition of clause 1, whereinthe carbon is characterized by one or more of the following: (1) adomain size ranging between around 15 Å and around 19 Å, (2) a domainsize ranging between around 19 Å and around 22 Å, (3) a domain sizeranging between around 24 Å and around 28 Å, and (4) a domain sizeranging between around 28 Å and 55 Å, and wherein the domain sizes areas estimated from the atomic pair distribution function G(r).

Clause 3. The lithium-ion battery anode composition of any of clauses 1to 2, wherein the carbon comprises porous carbon.

Clause 4. The lithium-ion battery anode composition of any of clauses 1to 3, wherein G(r=r₁) is a value of the atomic pair distributionfunction at a real space position of a first coordination sphere of thecarbon, wherein G(r=r₂) is a value of the atomic pair distributionfunction at a real space position of a second coordination sphere of thecarbon, and wherein a ratio G(r=r₁)/G(r=r₂) is in a range of around0.700 to around 0.590.

Clause 5. The lithium-ion battery anode composition of any of clauses 1to 4, wherein W(r=r₁) is a value of a full width at half maximum of theatomic pair distribution function at a real space position of a firstcoordination sphere of the carbon, wherein W(r=r₂) is a value of a fullwidth at half maximum of the atomic pair distribution function at a realspace position of a second coordination sphere of the carbon; andwherein a ratio W(r=r₁)/W(r=r₂) is in a range of around 0.700 to around0.850.

Clause 6. The lithium-ion battery anode composition of any of clauses 1to 5, wherein G(r=r₁) is a value of the atomic pair distributionfunction at a real space position of a first coordination sphere of thecarbon, wherein G(r=r₃) is a value of the atomic pair distributionfunction at a real space position of a third coordination sphere of thecarbon, and wherein a ratio G(r=r₁)/G(r=r₃) is in a range of around1.100 to around 1.300.

Clause 7. The lithium-ion battery anode composition of any of clauses 1to 6, wherein W(r=r₁) is a value of a full width at half maximum of theatomic pair distribution function at a real space position of a firstcoordination sphere of the carbon, wherein W(r=r₃) is a value of a fullwidth at half maximum of the atomic pair distribution function at a realspace position of a third coordination sphere of the carbon, and whereina ratio W(r=r₁)/W(r=r₃) is in a range of around 0.600 to around 0.850.

Clause 8. The lithium-ion battery anode composition of any of clauses 1to 7, wherein an anode comprising the anode composition exhibits anareal capacity loading that ranges from around 2 mAh/cm² to around 16mAh/cm².

Clause 9. The lithium-ion battery anode composition of clause 8, whereinfrom around 10% to around 100% of the areal capacity loading of theanode is provided by composite particles that are each configured as theporous composite particle.

Clause 10. The lithium-ion battery anode composition of any of clauses 8to 9, wherein the composite particles on average exhibit a silicon (Si)to carbon (C) weight ratio in the range from around 5:1 to 1:5.

Clause 11. The lithium-ion battery anode composition of any of clauses 1to 10, wherein the porous composite particle is characterized by anaverage scattering domain size (r), as estimated from the atomic pairdistribution function G(r), ranging from around 1 nm to around 40 nm.

Clause 12. The lithium-ion battery anode composition of clause 11,wherein the porous composite particle is characterized by the averagescattering domain size (r) ranging from around 1 nm to around 10 nm.

Clause 13. The lithium-ion battery anode composition of any of clauses 1to 12, wherein the porous composite particle on average comprises lessthan about 1 wt. % hydrogen (H), less than about 5 wt. % nitrogen (N)and less than about 2 wt. % oxygen (O).

Clause 14. The lithium-ion battery anode composition of any of clauses 1to 13, wherein the porous composite particle on average exhibits uptakefrom around 1.5 wt. % to around 25 wt. % nitrogen (N) when heated in anitrogen gas (N₂) at 1050° C. for a period of 2 hours, as measured on apowder that comprises the porous composite particle.

Clause 15. The lithium-ion battery anode composition of any of clauses 1to 14, wherein the porous composite particle exhibits average uptakefrom around 0.5 wt. % to around 10 wt. % nitrogen (N) when heated in anitrogen gas (N₂) at 850° C. for a period of 2 hours, as measured on apowder that comprises the porous composite particle.

Clause 16. The lithium-ion battery anode composition of any of clauses 1to 15, wherein the porous composite particle forms from around 1 wt. %to around 100 wt. % silicon carbide (SiC) when heated in a nitrogen gas(N₂) or in an argon gas (Ar) in a temperature range from around 750° C.to around 950° C. for a period of 2 hours or more, as detected by X-raydiffraction (XRD) or Fourier Transform Infrared Spectroscopy (FTIR).

Clause 17. The lithium-ion battery anode composition of any of clauses 1to 16, wherein the porous composite particle exhibits an averageBrunauer-Emmett-Teller (BET) specific surface area in the range fromaround 1 to around 40 m²/g, as measured using nitrogen sorption isothermon a powder that comprises the porous composite particle.

Clause 18. The lithium-ion battery anode composition of any of clauses 1to 17, wherein the porous composite particle exhibits average density inthe range from around 0.9 g/cm³ to around 2.2 g/cm³, as measured usingnitrogen or argon pycnometry on a powder that comprises the porouscomposite particle.

Clause 19. The lithium-ion battery anode composition of any of clauses 1to 18, wherein the porous composite particle exhibits volume-averageparticle size in the range from around 0.2 micron to around 20 microns,as measured using scanning electron microscope (SEM) image analysis orparticle scattering techniques on a powder that comprises the porouscomposite particle.

Clause 20. The lithium-ion battery anode composition of any of clauses 1to 19, wherein Raman spectra of the porous composite particle exhibitscarbon D and G peaks, wherein a ratio of average intensities of the D toG peaks (ID/IG) ranges from around 0.7 to around 2.7.

Clause 21. A Li-ion battery comprising: an anode comprising thelithium-ion battery anode composition of any of clauses 1 to 20, acathode that is electrically separated from the anode; and anelectrolyte ionically coupling the anode and the cathode.

Clause 22. The Li-ion battery of clause 21, wherein the battery capacityranges from around 0.2 Ah to around 400 Ah.

Clause 23. The Li-ion battery of any of clauses 21 to 22, whereinR(r=rSi—C) is a value of a radial distribution function R(r) at a realspace position of a first coordination sphere of a Si—C pair in theporous composite particle, wherein R(r=rC—C) is a value of the radialdistribution function R(r) at a real space position of a firstcoordination sphere of a C—C pair in the porous composite particle,wherein the radial distribution function R(r) and the atomic pairdistribution function are related by R(r)=R(r)=G(r)r+4πr²ρ₀, ρ₀ being aconstant relating to a number density of scatterers, and wherein a ratioR(r=rSi—C)/R(r=rC—C) is in a range of 0.050 to around 1.000.

Clause 24. A carbon material for use in making an anode composition foruse in a Li-ion battery, wherein the carbon material is characterized bya domain size (r), as estimated from an atomic pair distributionfunction G(r) obtained from a synchrotron x-ray diffraction measurementof the carbon material, ranging from around 10 Å (1 nm) to around 60 Å(6 nm).

Clause 25. The carbon material of clause 24, wherein the domain size (r)corresponds to one of the following: (1) a first domain size rangingbetween around 15 Å and around 19 Å, (2) a second domain size rangingbetween around 19 Å and around 22 Å, (3) a third domain size rangingbetween around 24 Å and around 28 Å, and (4) a fourth domain sizeranging between around 40 Å and 55 Å.

Clause 26. The carbon material of any of clauses 24 to 25, wherein thecarbon material comprises porous carbon.

Clause 27. The carbon material of any of clauses 24 to 26, whereinG(r=r₁) is a value of the atomic pair distribution function at a realspace position of a first coordination sphere of the carbon material,wherein G(r=r₂) is a value of the atomic pair distribution function at areal space position of a second coordination sphere of the carbonmaterial, and wherein a ratio G(r=r₁)/G(r=r₂) is in a range of around0.700 to around 0.590.

Clause 28. The carbon material of any of clauses 24 to 27, whereinW(r=r₁) is a value of a full width at half maximum of the atomic pairdistribution function at a real space position of a first coordinationsphere of the carbon material, wherein W(r=r₂) is a value of a fullwidth at half maximum of the atomic pair distribution function at a realspace position of a second coordination sphere of the carbon material,and wherein a ratio W(r=r₁)/W(r=r₂) is in a range of around 0.700 toaround 0.850.

Clause 29. The carbon material of any of clauses 24 to 28, whereinG(r=r₁) is a value of the atomic pair distribution function at a realspace position of a first coordination sphere of the carbon material,wherein G(r=r₃) is a value of the atomic pair distribution function at areal space position of a third coordination sphere of the carbonmaterial, and wherein a ratio G(r=r₁)/G(r=r₃) is in a range of around1.100 to around 1.300.

Clause 30. The carbon material of any of clauses 24 to 29, whereinW(r=r₁) is a value of a full width at half maximum of the atomic pairdistribution function at a real space position of a first coordinationsphere of the carbon material, wherein W(r=r₃) is a value of a fullwidth at half maximum of the atomic pair distribution function at a realspace position of a third coordination sphere of the carbon material,and wherein a ratio W(r=r₁)/W(r=r₃) is in a range of around 0.600 toaround 0.850.

This description is provided to enable any person skilled in the art tomake or use embodiments of the present invention. It will beappreciated, however, that the present invention is not limited to theparticular formulations, process stages, and materials disclosed herein,as various modifications to these embodiments will be readily apparentto those skilled in the art. That is, the generic principles definedherein may be applied to other embodiments without departing from thespirit or scope of the invention.

1. A lithium-ion battery anode composition, comprising: a porouscomposite particle comprising carbon (C) and an active materialcomprising silicon (Si), wherein the carbon is characterized by a domainsize (r), as estimated from an atomic pair distribution function G(r)obtained from a synchrotron x-ray diffraction measurement of the porouscomposite particle, ranging from around 10 Å (1 nm) to around 60 Å (6nm).
 2. The lithium-ion battery anode composition of claim 1, whereinthe carbon is characterized by one or more of the following: (1) adomain size ranging between around 15 Å and around 19 Å, (2) a domainsize ranging between around 19 Å and around 22 Å, (3) a domain sizeranging between around 24 Å and around 28 Å, and (4) a domain sizeranging between around 28 Å and 55 Å, and wherein the domain sizes areas estimated from the atomic pair distribution function G(r).
 3. Thelithium-ion battery anode composition of claim 1, wherein the carboncomprises porous carbon.
 4. The lithium-ion battery anode composition ofclaim 1, wherein G(r=r₁) is a value of the atomic pair distributionfunction at a real space position of a first coordination sphere of thecarbon, wherein G(r=r₂) is a value of the atomic pair distributionfunction at a real space position of a second coordination sphere of thecarbon, and wherein a ratio G(r=r₁)/G(r=r₂) is in a range of around0.700 to around 0.590.
 5. The lithium-ion battery anode composition ofclaim 1, wherein W(r=r₁) is a value of a full width at half maximum ofthe atomic pair distribution function at a real space position of afirst coordination sphere of the carbon, wherein W(r=r₂) is a value of afull width at half maximum of the atomic pair distribution function at areal space position of a second coordination sphere of the carbon; andwherein a ratio W(r=r₁)/W(r=r₂) is in a range of around 0.700 to around0.850.
 6. The lithium-ion battery anode composition of claim 1, whereinG(r=r₁) is a value of the atomic pair distribution function at a realspace position of a first coordination sphere of the carbon, whereinG(r=r₃) is a value of the atomic pair distribution function at a realspace position of a third coordination sphere of the carbon, and whereina ratio G(r=r₁)/G(r=r₃) is in a range of around 1.100 to around 1.300.7. The lithium-ion battery anode composition of claim 1, wherein W(r=r₁)is a value of a full width at half maximum of the atomic pairdistribution function at a real space position of a first coordinationsphere of the carbon, wherein W(r=r₃) is a value of a full width at halfmaximum of the atomic pair distribution function at a real spaceposition of a third coordination sphere of the carbon, and wherein aratio W(r=r₁)/W(r=r₃) is in a range of around 0.600 to around 0.850. 8.The lithium-ion battery anode composition of claim 1, wherein an anodecomprising the anode composition exhibits an areal capacity loading thatranges from around 2 mAh/cm² to around 16 mAh/cm².
 9. The lithium-ionbattery anode composition of claim 8, wherein from around 10% to around100% of the areal capacity loading of the anode is provided by compositeparticles that are each configured as the porous composite particle. 10.The lithium-ion battery anode composition of claim 8, wherein thecomposite particles on average exhibit a silicon (Si) to carbon (C)weight ratio in the range from around 5:1 to 1:5.
 11. The lithium-ionbattery anode composition of claim 1, wherein the porous compositeparticle is characterized by an average scattering domain size (r), asestimated from the atomic pair distribution function G(r), ranging fromaround 1 nm to around 40 nm.
 12. The lithium-ion battery anodecomposition of claim 11, wherein the porous composite particle ischaracterized by the average scattering domain size (r) ranging fromaround 1 nm to around 10 nm.
 13. The lithium-ion battery anodecomposition of claim 1, wherein the porous composite particle on averagecomprises less than about 1 wt. % hydrogen (H), less than about 5 wt. %nitrogen (N) and less than about 2 wt. % oxygen (O).
 14. The lithium-ionbattery anode composition of claim 1, wherein the porous compositeparticle on average exhibits uptake from around 1.5 wt. % to around 25wt. % nitrogen (N) when heated in a nitrogen gas (N₂) at 1050° C. for aperiod of 2 hours, as measured on a powder that comprises the porouscomposite particle.
 15. The lithium-ion battery anode composition ofclaim 1, wherein the porous composite particle exhibits average uptakefrom around 0.5 wt. % to around 10 wt. % nitrogen (N) when heated in anitrogen gas (N₂) at 850° C. for a period of 2 hours, as measured on apowder that comprises the porous composite particle.
 16. The lithium-ionbattery anode composition of claim 1, wherein the porous compositeparticle forms from around 1 wt. % to around 100 wt. % silicon carbide(SiC) when heated in a nitrogen gas (N₂) or in an argon gas (Ar) in atemperature range from around 750° C. to around 950° C. for a period of2 hours or more, as detected by X-ray diffraction (XRD) or FourierTransform Infrared Spectroscopy (FTIR).
 17. The lithium-ion batteryanode composition of claim 1, wherein the porous composite particleexhibits an average Brunauer-Emmett-Teller (BET) specific surface areain the range from around 1 to around 40 m²/g, as measured using nitrogensorption isotherm on a powder that comprises the porous compositeparticle.
 18. The lithium-ion battery anode composition of claim 1,wherein the porous composite particle exhibits average density in therange from around 0.9 g/cm³ to around 2.2 g/cm³, as measured usingnitrogen or argon pycnometry on a powder that comprises the porouscomposite particle.
 19. The lithium-ion battery anode composition ofclaim 1, wherein the porous composite particle exhibits volume-averageparticle size in the range from around 0.2 micron to around 20 microns,as measured using scanning electron microscope (SEM) image analysis orparticle scattering techniques on a powder that comprises the porouscomposite particle.
 20. The lithium-ion battery anode composition ofclaim 1, wherein Raman spectra of the porous composite particle exhibitscarbon D and G peaks, wherein a ratio of average intensities of the D toG peaks (I_(D)/I_(G)) ranges from around 0.7 to around 2.7.
 21. A Li-ionbattery comprising: an anode comprising the lithium-ion battery anodecomposition of claim 1; a cathode that is electrically separated fromthe anode; and an electrolyte ionically coupling the anode and thecathode.
 22. The Li-ion battery of claim 21, wherein the batterycapacity ranges from around 0.2 Ah to around 400 Ah.
 23. The Li-ionbattery of claim 21, wherein R(r=r_(Si—C)) is a value of a radialdistribution function R(r) at a real space position of a firstcoordination sphere of a Si—C pair in the porous composite particle,wherein R(r=r_(C—C)) is a value of the radial distribution function R(r)at a real space position of a first coordination sphere of a C—C pair inthe porous composite particle, wherein the radial distribution functionR(r) and the atomic pair distribution function are related byR(r)=G(r)r+4πr²ρ₀, ρ₀ being a constant relating to a number density ofscatterers, and wherein a ratio R(r=r_(Si—C))/R(r=r_(C—C)) is in a rangeof 0.050 to around 1.000.
 24. A carbon material for use in making ananode composition for use in a Li-ion battery, wherein the carbonmaterial is characterized by a domain size (r), as estimated from anatomic pair distribution function G(r) obtained from a synchrotron x-raydiffraction measurement of the carbon material, ranging from around 10 Å(1 nm) to around 60 Å (6 nm).
 25. The carbon material of claim 24,wherein the domain size (r) corresponds to one of the following: (1) afirst domain size ranging between around 15 Å and around 19 Å, (2) asecond domain size ranging between around 19 Å and around 22 Å, (3) athird domain size ranging between around 24 Å and around 28 Å, and (4) afourth domain size ranging between around 40 Å and 55 Å.
 26. The carbonmaterial of claim 24, wherein the carbon material comprises porouscarbon.
 27. The carbon material of claim 24, wherein G(r=r₁) is a valueof the atomic pair distribution function at a real space position of afirst coordination sphere of the carbon material, wherein G(r=r₂) is avalue of the atomic pair distribution function at a real space positionof a second coordination sphere of the carbon material, and wherein aratio G(r=r₁)/G(r=r₂) is in a range of around 0.700 to around 0.590. 28.The carbon material of claim 24, wherein W(r=r₁) is a value of a fullwidth at half maximum of the atomic pair distribution function at a realspace position of a first coordination sphere of the carbon material,wherein W(r=r₂) is a value of a full width at half maximum of the atomicpair distribution function at a real space position of a secondcoordination sphere of the carbon material, and wherein a ratioW(r=r₁)/W(r=r₂) is in a range of around 0.700 to around 0.850.
 29. Thecarbon material of claim 24, wherein G(r=r₁) is a value of the atomicpair distribution function at a real space position of a firstcoordination sphere of the carbon material, wherein G(r=r₃) is a valueof the atomic pair distribution function at a real space position of athird coordination sphere of the carbon material, and wherein a ratioG(r=r₁)/G(r=r₃) is in a range of around 1.100 to around 1.300.
 30. Thecarbon material of claim 24, wherein W(r=r₁) is a value of a full widthat half maximum of the atomic pair distribution function at a real spaceposition of a first coordination sphere of the carbon material, whereinW(r=r₃) is a value of a full width at half maximum of the atomic pairdistribution function at a real space position of a third coordinationsphere of the carbon material, and wherein a ratio W(r=r₁)/W(r=r₃) is ina range of around 0.600 to around 0.850.